Earth remote sensing technologies. The latest and promising satellites for remote sensing of the earth
Remote sensing of the Earth (ERS)- Observation of the Earth's surface by aviation and space means equipped with various types of imaging equipment. The operating range of wavelengths received by the imaging equipment ranges from fractions of a micrometer (visible optical radiation) to meters (radio waves). Sounding methods can be passive, that is, using the natural reflected or secondary thermal radiation of objects on the Earth's surface, due to solar activity, and active - using the stimulated radiation of objects initiated by an artificial source of directional action. Remote sensing data obtained from a spacecraft (SC) are characterized by a large degree of dependence on the transparency of the atmosphere. Therefore, the spacecraft uses multi-channel equipment of passive and active types, which detects electromagnetic radiation in various ranges.
Remote sensing equipment of the first spacecraft launched in the 1960s-70s. was of the track type - the projection of the measurement area on the Earth's surface was a line. Later, remote sensing equipment of a panoramic type appeared and became widespread - scanners, the projection of the measurement area on the Earth's surface of which is a strip.
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general review
Remote sensing is a method of obtaining information about an object or phenomenon without direct physical contact with this object. Remote sensing is a subset of geography. In the modern sense, the term mainly refers to airborne or spaceborne sensing technologies for the purpose of detecting, classifying and analyzing objects on the earth's surface, as well as the atmosphere and ocean, using propagated signals (for example, electromagnetic radiation). They are divided into active (the signal is first emitted by an aircraft or a space satellite) and passive remote sensing (only a signal from other sources, such as sunlight, is recorded).
Active devices, in turn, emit a signal in order to scan the object and space, after which the sensor is able to detect and measure the radiation reflected or formed by backscattering by the sensing target. Examples of active remote sensing sensors are radar and lidar, which measure the time delay between emitting and registering the returned signal, thus determining the location, speed, and direction of an object.
Remote sensing provides an opportunity to obtain data on dangerous, hard-to-reach and fast-moving objects, and also allows you to conduct observations over vast areas of the terrain. Examples of remote sensing applications would be monitoring deforestation (for example in the Amazon basin), glacier conditions in the Arctic and Antarctic, measuring ocean depth using a lot. Remote sensing also comes to replace expensive and relatively slow methods of collecting information from the Earth's surface, while at the same time guaranteeing the non-interference of man in natural processes in the observed territories or objects.
With orbiting spacecraft, scientists are able to collect and transmit data in various bands of the electromagnetic spectrum, which, combined with larger airborne and ground-based measurements and analysis, provide the necessary range of data to monitor current phenomena and trends, such as El Niño and others. natural phenomena, both in the short and long term. Remote sensing is also of applied importance in the field of geosciences (for example, nature management), agriculture (use and conservation of natural resources), national security (monitoring of border areas).
Data Acquisition Techniques
The main goal of multispectral studies and analysis of the obtained data is objects and territories that emit energy, which makes it possible to distinguish them from the background of the environment. A brief overview of satellite remote sensing systems is in the overview table.
As a rule, the best time to acquire data from remote sensing methods is summer time (in particular, during these months the sun is at its greatest angle above the horizon and the day length is longest). An exception to this rule is the acquisition of data using active sensors (eg Radar, Lidar), as well as thermal data in the long wavelength range. In thermal imaging, in which sensors measure thermal energy, it is better to use the time period when the difference between the ground temperature and air temperature is greatest. Thus, the best time for these methods is during the colder months, as well as a few hours before dawn at any time of the year.
In addition, there are some other considerations to take into account. With the help of radar, for example, it is impossible to obtain an image of the bare surface of the earth with a thick snow cover; the same can be said about lidar. However, these active sensors are insensitive to light (or lack thereof), making them an excellent choice for high latitude applications (for example). In addition, both radar and lidar are capable (depending on the wavelengths used) of capturing surface images under the forest canopy, making them useful for applications in heavily vegetated regions. On the other hand, spectral data acquisition methods (both stereo imaging and multispectral methods) are applicable mainly on sunny days; data collected in low light conditions tend to have low signal/noise levels, making them difficult to process and interpret. In addition, while stereo imaging is capable of depicting and identifying vegetation and ecosystems, it is not possible with this method (as with multispectral sounding) to penetrate tree canopies and acquire images of the earth's surface.
Application of remote sensing
Remote sensing is most often used in agriculture, geodesy, mapping, monitoring the surface of the earth and the ocean, as well as the layers of the atmosphere.
Agriculture
With the help of satellites, it is possible to receive images of individual fields, regions and districts with a certain cyclicity. Users can receive valuable information about the state of the land, including crop identification, crop area determination and crop status. Satellite data is used to accurately manage and monitor the results of farming at various levels. This data can be used for farm optimization and space-based management of technical operations. The images can help determine the location of crops and the extent of land depletion, and can then be used to develop and implement a treatment plan to locally optimize the use of agricultural chemicals. The main agricultural applications of remote sensing are as follows:
- vegetation:
- crop type classification
- assessment of the state of crops (monitoring of agricultural crops, damage assessment)
- yield assessment
- the soil
- display of soil characteristics
- soil type display
- soil erosion
- soil moisture
- mapping tillage practices
Forest cover monitoring
Remote sensing is also used to monitor forest cover and identify species. Maps obtained in this way can cover a large area, while displaying detailed measurements and characteristics of the area (type of trees, height, density). Using remote sensing data, it is possible to define and delineate different types of forest, which would be difficult to achieve using traditional methods on the surface of the earth. The data is available at a variety of scales and resolutions to suit local or regional requirements. The requirements for the detail of the terrain display depend on the scale of the study. To display changes in forest cover (texture, leaf density) apply:
- multispectral images: very high resolution data is needed for accurate species identification
- reusable images of the same territory are used to obtain information about seasonal changes of various types
- stereophotos - to distinguish between species, assess the density and height of trees. Stereo photographs provide a unique view of the forest cover, accessible only through remote sensing technology.
- Radars are widely used in the humid tropics due to their ability to acquire images in all weather conditions.
- Lidars make it possible to obtain a 3-dimensional forest structure, to detect changes in the height of the earth's surface and objects on it. Lidar data helps estimate tree heights, crown areas, and the number of trees per unit area.
Surface monitoring
Surface monitoring is one of the most important and typical applications of remote sensing. The obtained data are used in determining the physical state of the earth's surface, such as forests, pastures, road surfaces, etc., including the results of human activities, such as the landscape in industrial and residential areas, the state of agricultural areas, etc. Initially, a land cover classification system should be established, which usually includes land levels and classes. Levels and classes should be developed taking into account the purpose of use (national, regional or local level), spatial and spectral resolution of remote sensing data, user request, and so on.
Detection of changes in the state of the earth's surface is necessary to update land cover maps and rationalize the use of natural resources. Changes are typically detected when comparing multiple images containing multiple levels of data and, in some cases, when comparing old maps and updated remote sensing images.
- seasonal changes: farmland and deciduous forests change seasonally
- annual change: changes in land surface or land use, such as areas of deforestation or urban sprawl
Land surface information and land cover changes are essential for setting and implementing environmental protection policies and can be used with other data to perform complex calculations (eg erosion risks).
Geodesy
The collection of geodetic data from the air was first used to detect submarines and obtain gravity data used to build military maps. These data are the levels of instantaneous perturbations of the Earth's gravitational field, which can be used to determine changes in the distribution of the Earth's masses, which in turn can be required for various geological studies.
Acoustic and near-acoustic applications
- Sonar: passive sonar, registers sound waves coming from other objects (ship, whale, etc.); active sonar, emits pulses of sound waves and registers the reflected signal. Used to detect, locate and measure the parameters of underwater objects and terrain.
- Seismographs are a special measuring device that is used to detect and record all types of seismic waves. With the help of seismograms taken in different places of a certain territory, it is possible to determine the epicenter of an earthquake and measure its amplitude (after it has occurred) by comparing the relative intensities and the exact time of the oscillations.
- Ultrasound: ultrasonic radiation sensors that emit high-frequency pulses and record the reflected signal. Used to detect waves on the water and determine the water level.
When coordinating a series of large-scale observations, most sounding systems depend on the following factors: the location of the platform and the orientation of the sensors. High quality instruments now often use positional information from satellite navigation systems. Rotation and orientation are often determined by electronic compasses with an accuracy of about one to two degrees. Compasses can measure not only the azimuth (i.e., the degree deviation from magnetic north), but also the height (the deviation from sea level), since the direction of the magnetic field relative to the Earth depends on the latitude at which the observation takes place. For more accurate orientation, it is necessary to use inertial navigation, with periodic corrections by various methods, including navigation by stars or known landmarks.
Overview of the main remote sensing instruments
- Radars are mainly used in air traffic control, early warning, forest cover monitoring, agriculture and large scale meteorological data. Doppler radar is used by law enforcement agencies to monitor vehicle speeds, as well as to obtain meteorological data on wind speed and direction, location and intensity of precipitation. Other types of information received include data on ionized gas in the ionosphere. Artificial aperture interferometric radar is used to obtain accurate digital elevation models of large areas of terrain (see RADARSAT, TerraSAR-X, Magellan).
- Laser and radar altimeters on satellites provide a wide range of data. By measuring ocean level variations caused by gravity, these instruments display seafloor features with a resolution of about one mile. By measuring the height and wavelength of ocean waves with altimeters, you can find out the speed and direction of the wind, as well as the speed and direction of surface ocean currents.
- Ultrasonic (acoustic) and radar sensors are used to measure sea level, tide and tide, determine the direction of waves in coastal marine regions.
- Light Detection and Ranging (LIDAR) technology is well known for its military applications, in particular for laser projectile navigation. LIDAR is also used to detect and measure the concentration of various chemicals in the atmosphere, while LIDAR on board aircraft can be used to measure the height of objects and phenomena on the ground with greater accuracy than can be achieved with radar technology. Vegetation remote sensing is also one of the main applications of LIDAR.
- Radiometers and photometers are the most common instruments used. They capture the reflected and emitted radiation in a wide frequency range. Visible and infrared sensors are the most common, followed by microwave, gamma ray and, less commonly, ultraviolet sensors. These instruments can also be used to detect the emission spectrum of various chemicals, providing data on their concentration in the atmosphere.
- Stereo images obtained from aerial photography are often used in probing vegetation on the Earth's surface, as well as in the construction of topographic maps in the development of potential routes by analyzing images of the terrain, in combination with modeling of environmental features obtained by ground-based methods.
- Multispectral platforms such as Landsat have been in active use since the 1970s. These instruments have been used to generate thematic maps by taking images in multiple wavelengths of the electromagnetic spectrum (multi-spectrum) and are typically used on earth observation satellites. Examples of such missions include the Landsat program or the IKONOS satellite. Land cover and land use maps produced by thematic mapping can be used for mineral exploration, detection and monitoring of land use, deforestation, and the study of plant and crop health, including vast tracts of agricultural land or forested areas. Space imagery from the Landsat program is used by regulators to monitor water quality parameters, including Secchi depth, chlorophyll density, and total phosphorus. Weather satellites are used in meteorology and climatology.
- The method of spectral imaging produces images in which each pixel contains complete spectral information, displaying narrow spectral ranges within a continuous spectrum. Spectral imaging devices are used to solve various problems, including those used in mineralogy, biology, military affairs, and measurements of environmental parameters.
- As part of the fight against desertification, remote sensing makes it possible to observe areas that are at risk in the long term, determine the factors of desertification, assess the depth of their impact, and also provide the necessary information to those responsible for making decisions on taking appropriate environmental protection measures.
Data processing
With remote sensing, as a rule, processing of digital data is used, since it is in this format that remote sensing data is currently received. In digital format, it is easier to process and store information. A two-dimensional image in one spectral range can be represented as a matrix (two-dimensional array) of numbers I (i, j), each of which represents the intensity of radiation received by the sensor from the element of the Earth's surface, which corresponds to one image pixel.
The image consists of n x m pixels, each pixel has coordinates (i, j)- line number and column number. Number I (i, j)- an integer and is called the gray level (or spectral brightness) of the pixel (i, j). If the image is obtained in several ranges of the electromagnetic spectrum, then it is represented by a three-dimensional lattice consisting of numbers I (i, j, k), where k- spectral channel number. From a mathematical point of view, it is not difficult to process digital data obtained in this form.
In order to correctly reproduce an image from digital records supplied by information receiving points, it is necessary to know the record format (data structure), as well as the number of rows and columns. Four formats are used, which arrange the data as:
- zone sequence ( Band Sequental, BSQ);
- zones alternating in rows ( Band Interleaved by Line, BIL);
- zones alternating by pixels ( Band Interleaved by Pixel, BIP);
- a sequence of zones with information compression into a file using the group coding method (for example, in jpg format).
AT BSQ-format each zone image is contained in a separate file. This is convenient when there is no need to work with all zones at once. One zone is easy to read and visualize, zone images can be loaded in any order you want.
AT BIL-format zone data is written to one file line by line, while the zones alternate in lines: 1st line of the 1st zone, 1st line of the 2nd zone, ..., 2nd line of the 1st zone, 2- th line of the 2nd zone, etc. This entry is convenient when all zones are analyzed simultaneously.
AT BIP-format the zonal values of the spectral brightness of each pixel are stored sequentially: first, the values of the first pixel in each zone, then the values of the second pixel in each zone, and so on. This format is called combined. It is convenient when performing per-pixel processing of a multi-zone image, for example, in classification algorithms.
Group coding used to reduce the amount of raster information. Such formats are convenient for storing large snapshots; to work with them, you need to have a data unpacking tool.
Image files usually come with the following additional image-related information:
- description of the data file (format, number of rows and columns, resolution, etc.);
- statistical data (brightness distribution characteristics - minimum, maximum and average value, dispersion);
- map projection data.
Additional information is contained either in the header of the image file or in a separate text file with the same name as the image file.
According to the degree of complexity, the following levels of processing of CS provided to users are distinguished:
- 1A is a radiometric correction of distortions caused by differences in sensitivity of individual sensors.
- 1B - radiometric correction at processing level 1A and geometric correction of systematic sensor distortions, including panoramic distortions, distortions caused by the rotation and curvature of the Earth, fluctuations in the height of the satellite orbit.
- 2A - image correction at level 1B and correction in accordance with a given geometric projection without the use of ground control points. For geometric correction, a global digital elevation model is used ( DEM, DEM) with a step on the ground of 1 km. The geometric correction used eliminates systematic sensor distortions and projects the image into a standard projection ( UTM WGS-84), using known parameters (satellite ephemeris data, spatial position, etc.).
- 2B - image correction at level 1B and correction in accordance with a given geometric projection using control ground points;
- 3 - image correction at the 2B level plus correction using terrain DEM (ortho-rectification).
- S - image correction using a reference image.
The quality of data obtained from remote sensing depends on their spatial, spectral, radiometric and temporal resolution.
Spatial resolution
It is characterized by the size of a pixel (on the surface of the Earth), recorded in a raster image - usually varies from 1 to 4000 meters.
Spectral resolution
Landsat data includes seven bands, including infrared, ranging from 0.07 to 2.1 µm. The Hyperion sensor of Earth Observing-1 is capable of recording 220 spectral bands from 0.4 to 2.5 µm, with a spectral resolution of 0.1 to 0.11 µm.
Radiometric resolution
The number of signal levels that the sensor can register. Usually varies from 8 to 14 bits, which gives from 256 to 16,384 levels. This characteristic also depends on the noise level in the instrument.
Temporary permission
The frequency of the satellite passing over the area of interest. It is of value in the study of series of images, for example, in the study of forest dynamics. Initially, series analysis was carried out for the needs of military intelligence, in particular, to track changes in infrastructure and enemy movements.
To create accurate maps based on remote sensing data, a transformation is needed to eliminate geometric distortions. An image of the Earth's surface with a device directed exactly down contains an undistorted image only in the center of the image. As you move towards the edges, the distances between points on the image and the corresponding distances on the Earth become more and more different. Correction of such distortions is carried out in the process of photogrammetry. Since the early 1990s, most commercial satellite images have been sold already corrected.
In addition, radiometric or atmospheric correction may be required. Radiometric correction converts discrete signal levels, such as 0 to 255, into their true physical values. Atmospheric correction eliminates the spectral distortions introduced by the presence of the atmosphere.
As part of the NASA Earth Observing System program, the levels of remote sensing data processing were formulated:
| Level | Description |
|---|---|
| 0 | Data coming directly from the device, without overhead (sync frames, headers, repeats). |
| 1a | Reconstructed device data provided with time markers, radiometric coefficients, ephemeris (orbital coordinates) of the satellite. |
| 1b | Level 1a data converted to physical units. |
| 2 | Derived geophysical variables (ocean wave height, soil moisture, ice concentration) with the same resolution as Tier 1 data. |
| 3 | Variables displayed in the universal space-time scale, possibly supplemented by interpolation. |
| 4 | Data obtained as a result of calculations based on previous levels. |
Training and education
In most higher education institutions, remote sensing is taught in the departments of geography. The relevance of remote sensing is constantly increasing in the modern information society. This discipline is one of the key technologies of the aerospace industry and is of great economic importance - for example, the new TerraSAR-X and RapidEye sensors are constantly being developed, and the demand for skilled labor is also constantly growing. In addition, remote sensing has an extremely large impact on daily life, from weather reporting to climate change and natural disaster forecasting. As an example, 80% of German students use Google Earth; in 2006 alone, the program was downloaded 100 million times. However, studies show that only a small fraction of these users have fundamental knowledge of the data they work with. There is currently a huge knowledge gap between the use and understanding of satellite imagery. The teaching of remote sensing principles is very superficial in the vast majority of educational institutions, despite the urgent need to improve the quality of teaching in this subject. Many of the computer software products specifically designed for the study of remote sensing have not yet been introduced into the educational system, mainly because of their complexity. Thus, in many cases, this discipline is either not included in the curriculum at all, or does not include a course in the scientific analysis of analog images. In practice, the subject of remote sensing requires a consolidation of physics and mathematics, as well as a high level of competence in the use of tools and techniques other than simple visual interpretation of satellite images.
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1. Basic concepts of remote sensing of the Earth. Remote sensing scheme
remote sensing earth geodetic
Remote sensing of the Earth (ERS) - obtaining information about the surface of the Earth and objects on it, the atmosphere, the ocean, the upper layer of the earth's crust by non-contact methods, in which the recording device is removed from the object of study at a considerable distance.
The physical basis of remote sensing is the functional relationship between the registered parameters of the object's own or reflected radiation and its biogeophysical characteristics and spatial position.
Remote sensing is used to study the physical and chemical properties of objects.
There are two interrelated directions in remote sensing
Natural science (remote research)
Engineering (remote methods)
remote sensing
remote sensing techniques
The subject of remote sensing as a science is the spatio-temporal properties and relationships of natural and socio-economic objects, manifested directly or indirectly in their own or reflected radiation, remotely recorded from space or from the air in the form of a two-dimensional image - a snapshot.
Remote sensing methods are based on the use of sensors that are placed on spacecraft and register electromagnetic radiation in formats that are much more suitable for digital processing, and in a much wider range of the electromagnetic spectrum.
In remote sensing, the infrared range of reflected radiation, thermal infrared and radio range of the electromagnetic spectrum are used.
The process of collecting remote sensing data and using it in geographic information systems (GIS).
2. Types of space surveys
Space photography occupies one of the leading places among the various methods of remote sensing. It is carried out using:
* artificial satellites of the Earth (ISS),
* interplanetary automatic stations,
* long-term orbital stations,
* manned spacecraft.
Tab. The main spaceports used for launching surveyor satellites.
Space systems (complexes) for monitoring the environment include (and perform):
1. Satellite systems in orbit (mission and survey control center),
2. Reception of information by ground receiving points, relay satellites,
3. Storage and distribution of materials (primary processing centers, image archives). An information retrieval system has been developed that ensures the accumulation and systematization of materials received from artificial Earth satellites.
Orbits of spacecraft.
Carrier orbits are divided into 3 types:
* equatorial,
* polar (pole),
* oblique.
Orbits are divided into:
* circular (more precisely, close to circular). Satellite images obtained from a space carrier that moved in a circular orbit have approximately the same scale.
* elliptical.
Orbits are also distinguished by their position relative to the Earth or the Sun:
* geosynchronous (relative to the Earth)
* heliosynchronous (relative to the Sun).
Geosynchronous - a spacecraft moves with an angular velocity equal to the speed of the Earth's rotation. This creates the effect of the space carrier “hovering” at one point, which is convenient for continuous surveys of the same area of the earth's surface.
Heliosynchronous (or sun-synchronous) - a spacecraft passes over certain areas of the earth's surface at the same local time, which is used in the production of multiple surveys under the same lighting conditions. Heliosynchronous orbits - orbits, when shooting from which the solar illumination of the earth's surface (the height of the Sun) remains practically unchanged for quite a long time (almost during the Season). This is achieved in the following way. Since the plane of any orbit, under the influence of the non-sphericity of the Earth, unfolds a little (precesses), it turns out that by choosing a certain ratio of inclination and height of the orbit, it is possible to achieve that the magnitude of the precession is equal to the daily rotation of the Earth around the Sun, i.e., about 1 ° per day. Among near-Earth orbits, it is possible to create only a few sun-synchronous orbits, the inclination of which is always reversed. For example, at an orbit altitude of 1000 km, the inclination should be 99°.
Shooting types.
Space imaging is carried out by different methods (Fig. "Classification of space images by spectral ranges and imaging technology").
According to the nature of the coverage of the earth's surface by satellite images, the following surveys can be distinguished:
* single photography,
* route,
* sighting,
* global shooting.
Single (selective) photographing is carried out by astronauts with hand-held cameras. Pictures are usually obtained perspective with significant angles of inclination.
Route survey of the earth's surface is carried out along the path of the satellite. The survey swath width depends on the flight altitude and the viewing angle of the imaging system.
Aimed (selective) survey is designed to obtain images of specially specified areas of the earth's surface away from the road.
Global imaging is carried out from geostationary and polar-orbiting satellites. satellites. Four or five geostationary satellites in equatorial orbit provide practically continuous acquisition of small-scale panoramic images of the entire Earth (space patrols) except for the polar caps.
aerospace image
An aerospace image is a two-dimensional image of real objects, which is obtained according to certain geometric and radiometric (photometric) laws by remote registration of the brightness of objects and is intended to study visible and hidden objects, phenomena and processes of the surrounding world, as well as to determine their spatial position.
A space image in its geometric properties does not fundamentally differ from an aerial photograph, but has features associated with:
* photographing from great heights,
* and high speed.
Aerospace photography is performed in the visible and invisible ranges of electromagnetic waves, where:
1. photographic - visible range;
2. non-photographic - visible and invisible ranges, where:
· visible range - spectrometric is based on the difference in the spectral reflection coefficients of geological objects. The results are recorded on magnetic tape and marked on the map. It is possible to use film and photo cameras;
Invisible range: radar (radiothermal RT and radar radar), ultraviolet UV, infrared IR, optoelectronic (scanner), laser (lidar).
Visible and near infrared region. The most complete amount of information is obtained in the most developed visible and near infrared regions. Aerial and space surveys in the visible and near infrared wavelength ranges are carried out using the following systems:
* Television,
* photographic,
* optoelectronic scanning,
3. Photographic systems
Currently, there is a wide class of remote sensing systems
forming an image of the underlying surface under study. Within this class of equipment, several subclasses can be distinguished that differ in the spectral range of the electromagnetic radiation used and in the type of detected radiation receiver, also according to the active or passive method (photographic and phototelevision sounding systems: scanning systems of the visible and IR ranges, television optical - mechanical and optical-electronic scanning radiometers and multispectral scanners; television optical systems: side-scan radar systems (RLSBO);
Photographic images of the Earth's surface are obtained from manned spacecraft and orbital stations or from automatic satellites. A distinctive feature of satellite images (CS) is a high degree
visibility coverage of large surface areas with one image - Depending on the type of equipment used and photographic films, photography can be carried out in the entire visible range of the electromagnetic spectrum in its individual zones, as well as in the near IR (infrared) range
The scale of the survey depends on the two most important parameters of the survey height and the focal length of the lens - Space cameras, depending on the inclination of the optical axis, allow you to obtain planned and perspective images of the earth's surface. Currently, high-resolution photographic equipment is used that allows you to obtain (CS) with an overlap of 60% or more - The spectral range of photographing covers the visible part of the near infrared zone (up to 0.86 microns). The well-known shortcomings of the photographic method are associated with the need to return the film to Earth and its limited supply on board. However, photographic shooting is currently the most informative type of shooting from outer space - the optimal print size is 18x18 cm, which, as experience shows, is consistent with the physiology of human vision, allowing you to see the entire image at the same time. topographic reference of control points with an accuracy of 0.1 mm or more. For the installation of photo schemes, only planned CSs are used
To bring a multi-scale usually promising CS to the planned one, a special process called transformation is used.
4. Television systems
TV and scanner pictures. Television and scanner photography makes it possible to systematically obtain images and transmit them to Earth at receiving stations. Personnel and scanning systems are used. In the first case, this is a miniature television camera in which the optical image built by the lens on the screen is converted into the form of electrical signals and transmitted to the ground via radio channels - In the second case, the swinging mirror of the scanner on board captures the light flux reflected from the Earth, which enters the photomultiplier. The converted scanner signals are transmitted to the Earth via radio channels. At receiving stations, they are recorded as images. Vibrations of the mirror form lines of the image, the movement of the carrier allows you to accumulate lines and form an image. Television and scanner images can be transmitted in real time, i.e. during the passage of the satellite over the subject. Efficiency is the hallmark of this method. However, the quality of the images is somewhat inferior to photographic images. The resolution of scanner images is determined by the scanning element and is currently 80-30 m. Images of this type are distinguished by a line-grid structure that is noticeable only when zoomed in on high-resolution images. Scanner images of large coverage have significant geometric distortions. Scanned images are received in digital form, which facilitates computer processing.
Television and scanner shooting is carried out from meteorological satellites and resource satellites LandSat, Meteor-Priroda, Resource 0. In a multi-zone version.
Earth orbits with a height of 600-1400 km., Scales from 1:10,000,000 to 1:1,000,000 and 1:100,000 with a resolution of 1-2 km to 30 m. LandSat, for example, has 4 spectral imaging ranges in the visible and near infrared range with a resolution of 30 m. "Meteor-Nature" scanners allow you to get a small (1.5 km), medium (230 m) and high resolution up to 80-40 m, Resource -0 medium (170 m) and high (40 m) scanners .
Multi-element CCD images. A further increase in resolution with the speed of shooting is associated with the introduction of electronic cameras. They use multi-element linear and matrix radiation receivers, consisting of charge-coupled devices (light-sensitive detector elements). A linear array of detectors implements a snapshot row, the accumulation of rows due to the movement of the carrier. (similar to a scanner), but no oscillating mirrors and higher resolution. High-resolution resource images (40m) Resource and French SPOT satellite, up to 10 m. In phototelevision, photographing with a camera (resulting in good quality), and transmission via television channels - Thus, the advantages of photography with its high resolution and prompt delivery of images are combined.
5. Scanner systems
At present, for surveys from space, multispectral (multispectral) cameras are most often used. optical-mechanical systems - scanners installed on satellites for various purposes. With the help of scanners, images are formed, consisting of many separate, sequentially obtained elements. The term "scanning" means scanning the image using a scanning element (a swinging or rotating mirror), which scans the area element by element across the movement of the carrier and sends a radiant flux to the lens and then to a point sensor that converts the light signal into an electrical one.
This electrical signal is sent to receiving stations via communication channels. The image of the terrain is obtained continuously on a tape composed of stripes - scans, folded by individual elements - pixels. Scanner images can be obtained in all spectral ranges, but the visible and IR ranges are especially effective. When shooting the earth's surface with the help of scanning systems, an image is formed, each element of which corresponds to the brightness of the radiation of the area located within the instantaneous field of view. A scanner image is an ordered packet of brightness data transmitted via radio channels to the Earth, which is recorded on a magnetic tape (in digital form) and then can be converted to a frame form. The most important characteristics of the scanner are the scanning (viewing) angle and the instantaneous angle of view, the magnitude of which determines the width of the filmed strip and resolution. Depending on the size of these angles, scanners are divided into accurate and survey. For precision scanners, the scanning angle is reduced to ±5°, and for survey scanners, it is increased to ±50°. The resolution value is inversely proportional to the width of the filmed band. A new generation scanner, called the "thematic cartographer", which was equipped with American satellites, has proven itself well
Landsat 5 and Landsat 7. The “thematic mapper” type scanner operates in seven bands with a resolution of 30m in the visible range of the spectrum and 120m in the IR range. This scanner gives a large flow of information, the processing of which requires more time; in connection with this, the image transmission speed slows down (the number of pixels in the images reaches more than 36 million on each of the channels). Scanning devices can be used not only to obtain images of the Earth, but also to measure radiation scanning radiometers, and scanning radiation - spectrometers.
6. Laser scanning systems
Just ten years ago, it was very difficult to even imagine that they would create a device that could make up to half a million complex measurements in one second. Today, such devices are not only created, but also very widely used.
Laser scanning systems - it is already difficult to do without them in many industries, such as mining, industry, topographic survey, architecture, archeology, civil engineering, monitoring, city modeling and more.
The fundamental technical parameters of terrestrial laser scanners are the speed, accuracy and range of measurements. The choice of model largely depends on the types of work and objects on which the scanners will be used. For example, in large quarries, it is better to use devices with increased accuracy and range. For architectural work, a range of 100-150 meters is quite enough, but a device with an accuracy of up to 1 cm is required. If we talk about the speed of work, then in this case, the higher, the better, of course.
Recently, ground-based laser scanning technology has been increasingly used to solve engineering geodesy problems in various areas of construction and industry. The growing popularity of laser scanning is due to a number of advantages that the new technology provides compared to other measurement methods. Among the advantages, I would like to highlight the main ones: an increase in the speed of work and a decrease in labor costs. The emergence of new, more productive models of scanners, the improvement of software capabilities, allows us to hope for a further expansion of the scope of terrestrial laser scanning.
The first scan result is a point cloud, which carries the maximum information about the object under study, be it a building, an engineering structure, an architectural monument, etc. Using the point cloud in the future, it is possible to solve various problems:
Obtaining a three-dimensional model of the object;
Obtaining drawings, including drawings of sections;
Identification of defects and various designs by comparison with the design model;
· determination and evaluation of strain values by means of comparison with previously made measurements;
Obtaining topographic plans by the method of virtual survey.
When surveying complex industrial facilities using traditional methods, performers often face the fact that certain measurements are missed during field work. The abundance of contours, a large number of individual objects lead to inevitable errors. The materials obtained by laser scanning carry more complete information about the subject. Before starting the scanning process, the laser scanner takes panoramic photographs, which significantly increases the information content of the results obtained.
Terrestrial laser scanning technology used to create three-dimensional models of objects, topographic plans of complex loaded territories, significantly increases labor productivity and reduces time costs. The development and implementation of new technologies for the production of geodetic works have always been carried out in order to reduce the time of field work. It is safe to say that laser scanning fully complies with this principle.
Terrestrial laser scanning technology is in constant development. This also applies to the improvement of the design of laser scanners, and the development of software functions used to control devices and process the results obtained.
7. Stefan-Boltzmann law
Heated bodies radiate energy in the form of electromagnetic waves of various lengths. When we say that a body is "red-hot", it means that its temperature is high enough for thermal radiation to occur in the visible, light part of the spectrum. At the atomic level, radiation becomes a consequence of the emission of photons by excited atoms. The law describing the dependence of the energy of thermal radiation on temperature was obtained on the basis of an analysis of experimental data by the Austrian physicist Josef Stefan and theoretically substantiated also by the Austrian Ludwig Boltzmann.
To understand how this law works, imagine an atom emitting light in the bowels of the Sun. Light is immediately absorbed by another atom, re-emitted by it - and thus transmitted along the chain from atom to atom, due to which the whole system is in a state of energy balance. In an equilibrium state, light of a strictly defined frequency is absorbed by one atom in one place simultaneously with the emission of light of the same frequency by another atom in another place. As a result, the light intensity of each wavelength of the spectrum remains unchanged.
The temperature inside the Sun drops as you move away from its center. Therefore, as you move towards the surface, the spectrum of light radiation is corresponding to higher temperatures than the ambient temperature. As a result, during repeated emission, according to the Stefan-Boltzmann law, it will occur at lower energies and frequencies, but at the same time, due to the law of conservation of energy, a larger number of photons will be emitted. Thus, by the time it reaches the surface, the spectral distribution will correspond to the temperature of the surface of the Sun (about 5,800 K), and not to the temperature at the center of the Sun (about 15,000,000 K). The energy that comes to the surface of the Sun (or to the surface of any hot object) leaves it in the form of radiation. The Stefan-Boltzmann law just tells us what the radiated energy is. This law is written like this:
where T is the temperature (in kelvins) and y is Boltzmann's constant. It can be seen from the formula that as the temperature rises, the luminosity of the body not only increases, but increases to a much greater extent. Double the temperature and the luminosity will increase 16 times!
So, according to this law, any body that has a temperature above absolute zero radiates energy. So why, one wonders, have not all bodies cooled down to absolute zero for a long time? Why, say, your body, constantly radiating thermal energy in the infrared range, characteristic of the temperature of the human body (slightly more than 300 K), does not cool down?
The answer to this question is actually two parts. Firstly, with food you get energy from the outside, which in the process of metabolic assimilation of food calories by the body is converted into thermal energy, which replenishes the energy lost by your body in accordance with the Stefan-Boltzmann law. A dead warm-blooded animal cools down to ambient temperature very quickly, since the energy supply to its body stops.
Even more important, however, is the fact that the law applies to all bodies without exception with a temperature above absolute zero. Therefore, when giving your thermal energy to the environment, do not forget that the bodies to which you give energy - for example, furniture, walls, air - in turn radiate thermal energy, and it is transferred to you. If the environment is colder than your body (as is most often the case), its thermal radiation compensates for only a part of the heat losses of your body, and it makes up for the deficit using internal resources. If the ambient temperature is close to or higher than your body temperature, you will not be able to get rid of the excess energy released in your body during metabolism through radiation. And then the second mechanism comes into play. You begin to sweat, and along with sweat droplets, excess heat leaves your body through the skin.
In the above formulation, the Stefan-Boltzmann law applies only to an absolutely black body, which absorbs all radiation falling on its surface. Real physical bodies absorb only part of the ray energy, and the rest is reflected by them, however, the pattern according to which the specific power of radiation from their surface is proportional to T 4, as a rule, is also preserved in this case, however, in this case, the Boltzmann constant has to be replaced by another coefficient , which will reflect the properties of a real physical body. Such constants are usually determined experimentally.
8. History of remote sensing methods development
Drawn images - Photographs - ground phototheodolite survey - Aerial photographs - aerial methods. - The concept of remote sensing appeared in the 19th century. - Subsequently, remote sensing began to be used in the military field to collect information about the enemy and make strategic decisions. - After World War II, remote sensing began to be used for observation for the environment and assessment of the development of territories, as well as in civil cartography.
In the 60s of the XX century, with the advent of space rockets and satellites, remote sensing went into space. -1960 - the launch of reconnaissance satellites as part of the CORONA, ARGON and LANYARD programs. -Program Mercury - received images of the Earth. Project Gemini (1965-1966) - systematic collection of remote sensing data. Apollo program (1968-1975) - remote sensing of the earth's surface and landing a man on the Moon - Launch of the Skylab space station (1973-1974), - exploration of earth resources. Flights of space shuttles (1981). Obtaining multi-zone images with a resolution of 100 meters in the visible and near infrared range using nine spectral channels.
9. Elements of orientation of space images
The position of the image at the time of photographing is determined by three elements of internal orientation - the focal length of the camera f, the coordinates x0, y0 of the main point o (Fig. 1) and six elements of external orientation - the coordinates of the projection center S - XS, YS, ZS, the longitudinal and transverse tilt angles of the image b and u and angle of rotation h.
There is a connection between the coordinates of the object point and its image in the image:
where X, Y, Z and XS, YS, ZS are the coordinates of points M and S in the OXYZ system; X", Y", Z" - coordinates of the point m in the SXYZ system parallel to OXYZ, calculated from the x and y plane coordinates:
a1 \u003d cos bcosch - sinbsinschsinch
a2 \u003d - cossinch - sinbsin schcosch
a3 \u003d - sinаcos u
b2 = cosschcosch (3)
c1 \u003d sinbcosch + cosbsinschsinch,
c2 \u003d - sinbcosch + cosbsinschcosch,
Direction cosines.
The formulas for the connection between the coordinates of the point M of the object (Fig. 2) and the coordinates of its images m1 and m2 on the stereopair P1 - P2 have the form:
BX, BY and BZ - projections of the basis B on the coordinate axes. If the exterior orientation elements of the stereopair are known, then the coordinates of the object point can be determined by formula (4) (direct resection method). Using a single image, the position of an object's point can be found in the particular case when the object is flat, for example, flat terrain (Z = const). The x and y coordinates of the image points are measured using a monocomparator or a stereocomparator. Interior orientation elements are known from camera calibration results, and exterior orientation elements can be determined when photographing an object or during phototriangulation (See Phototriangulation). If the exterior orientation elements of images are unknown, then the coordinates of the object point are found using reference points (resection method). Reference point - a contour point of an object identified in the image, the coordinates of which are obtained as a result of geodetic measurements or from phototriangulation. Using a resection, first determine the elements of the relative orientation of the images P1 - P2 (Fig. 3) - b "1, h" 1, a "2, y" 2, h "2 in the S1X"Y"Z" system; the X axis of which coincides with the basis, and the Z axis lies in the main basal plane S1O1S2 of the image P1. Then the coordinates of the points of the model are calculated in the same system. Finally, using anchor points, transition. from model point coordinates to object point coordinates.
Relative orientation elements allow you to set the images in the same position relative to each other that they occupied when photographing the object. In this case, each pair of respective rays, for example S1m1 and S2m2, intersect and form a point (m) of the model. The set of rays belonging to the image is called a ligament, and the projection center - S1 or S2 - is called the vertex of the ligament. The scale of the model remains unknown because the distance S1S2 between the vertices of the ligaments is chosen arbitrarily. The corresponding points of the stereopair m1 and m2 are in the same plane passing through the S1S2 basis. Therefore
Assuming that the approximate values of the relative orientation elements are known, we can represent equation (6) in a linear form:
a db1" + b db2" + s dsch2" + d dch1" + e dch2" + l = V, (7)
where db1",... e dm2" are corrections to the approximate values of the unknowns, a,..., e are the partial derivatives of the function (6) with respect to the variables b1",... h2", l is the value of the function (6) , calculated from approximate values known to me. To determine the elements of relative orientation, the coordinates of at least five points of the stereopair are measured, and then equations (7) are compiled and solved by the method of successive approximations. The coordinates of the points of the model are calculated according to formulas (4), choosing the length of the basis B arbitrarily and assuming
Xs1 = Ys1 = Zs1 = 0, BX = B, BY = BZ = 0.
In this case, the spatial coordinates of the points m1 and m2 are found by formulas (2), and the direction cosines are found by formulas (3): for the image P1, by the elements b1",
and for the snapshot P2 by the elements b2", w2", h2".
According to the X" Y" Z" coordinates, the model points determine the coordinates of the object point:
where t is the denominator of the model scale. Direction cosines are obtained by formulas (3), substituting instead of the angles b, u and h the longitudinal angle of the model o, the transverse angle of the model z and the angle of rotation of the model u.
To determine the seven elements of the exterior orientation of the model - Posted at http://www.allbest.ru/
O, z, u, t - make equations (8) for three or more reference points and solve them. The coordinates of the control points are found by geodetic methods or by the method of phototriangulation. The set of points of the object, the coordinates of which are known, forms a digital model of the object, which serves to draw up a map and solve various engineering problems, for example, to find the optimal road route. In addition to analytical methods for processing images, analog ones are used, based on the use of photogrammetric devices - Phototransformer, Stereograph, Stereoprojector, etc.
Slit and panoramic photographs, as well as photographs obtained with the use of radar, television, infrared-thermal, and other imaging systems, significantly expand the possibilities of photographic imaging, especially in space research. But they do not have a single projection center, and their external orientation elements are continuously changing in the process of imaging, which complicates the use of such images for measurement purposes.
10. Properties of aerospace images
Aerospace images are the main result of aerospace surveys, which use a variety of aviation and space media. This is a two-dimensional image of real objects, which was obtained according to certain geometric and radiometric (photometric) laws by remote registration of the brightness of objects and is intended to study visible and hidden objects, phenomena and processes of the surrounding world, as well as to determine their spatial position. Aerospace surveys are divided into passive ones, which provide for the registration of reflected solar or Earth's own radiation; active, in which registration of reflected artificial radiation is performed. Scale range of aerospace images: from 1:1000 to 1:100,000,000
The most common scales: aerial photographs 1:10,000 - 1:50,000, space - 1:200,000 - 1:10,000,000.
Aerospace images: analog (usually photographic), digital (electronic). The image of digital photographs is formed from separate identical elements - pixels (from the English picture element - pxel); the brightness of each pixel is characterized by one number. Properties of aerospace images: Graphic, Radiometric (photometric), Geometric.
Visual properties characterize the ability of photographs to reproduce fine details, colors and tonal gradations of objects.
Radiometric ones testify to the accuracy of the quantitative registration of the brightness of objects by a snapshot.
Geometrical characterize the possibility of determining the sizes, lengths and areas of objects and their relative position from images.
11. Displacement of points on a satellite image
Advantages of space photography. The flying satellite does not experience vibrations and sharp fluctuations; therefore, satellite images can be obtained with a higher resolution and high image quality than aerial photographs. Pictures can be digitized for subsequent computer processing.
Disadvantages of satellite imagery: information cannot be processed automatically without preliminary transformations. During space photography, points shift (under the influence of the curvature of the Earth), their value at the edges of the image reaches 1.5 mm. Scale constancy is broken within the image, the difference between which at the edges and in the center of the image can be more than 3%.
The disadvantage of photography is its inefficiency, tk. the container with the film descends to Earth no more than once every few weeks. Therefore, photographic satellite images are rarely used for operational purposes, but represent information of long-term use.
As you know, a snapshot is a central projection of the terrain, and a topographic map is orthogonal. A horizontal image of a flat area corresponds to an orthogonal projection, i.e., a projection of a limited section of a topographic map. In this regard, if you convert an oblique image into a horizontal image of a given scale, then the position of the contours on the image will correspond to the position of the contours on a topographic map of a given scale. The terrain also causes the points on the image to shift relative to their position on the orthogonal projection of the corresponding scale.
12. Stages of remote sensing and data analysis
Stereo shooting.
Multi-zone shooting. Hyperspectral photography.
Multiple shooting.
Multilevel shooting.
Multipolar shooting.
Combined method.
Interdisciplinary analysis.
Technique for obtaining remote sensing materials
Aerospace photography is carried out in atmospheric transparency windows using radiation in different spectral ranges - light (visible, near and mid-infrared), thermal infrared and radio ranges.
Photography
High degree of visibility, coverage of large surface areas with one image.
Photographing in the entire visible range of the electromagnetic spectrum, in its individual zones, as well as in the near IR (infrared) range.
Shooting scale depends on
Shooting Heights
The focal length of the lens.
Depending on the inclination of the optical axis, obtaining planned and perspective images of the earth's surface.
COP with an overlap of 60% or more. The spectral range of photographing covers the visible part of the near infrared zone (up to 0.86 microns).
Scanner shooting
The most commonly used are multispectral optical-mechanical systems - scanners installed on satellites for various purposes.
Images that are made up of many individual, sequentially acquired elements.
"scanning" - scanning the image using a scanning element that scans the area element by element across the movement of the carrier and sends a radiant flux to the lens and then to a point sensor that converts the light signal into an electrical one. This electrical signal is sent to receiving stations via communication channels. The image of the terrain is obtained continuously on a tape composed of stripes - scans, folded by individual elements - pixels.
Scanner shooting
Scanner images can be obtained in all spectral ranges, but the visible and IR ranges are especially effective.
The most important characteristics of the scanner are the scanning (viewing) angle and the instantaneous angle of view, the magnitude of which determines the width of the filmed strip and resolution. Depending on the size of these angles, scanners are divided into accurate and survey.
For precision scanners, the scanning angle is reduced to ±5°, and for survey scanners, it is increased to ±50°. The resolution value is inversely proportional to the width of the filmed band.
Radar survey
Obtaining images of the earth's surface and objects located on it, regardless of weather conditions, in the daytime and at night, thanks to the principle of active radar.
The technology was developed in the 1930s.
Radar survey of the Earth is carried out in several sections of the wavelength range (1 cm - 1 m) or frequencies (40 GHz - 300 MHz).
The nature of the image on a radar image depends on the relationship between the wavelength and the size of the terrain irregularities: the surface can be rough or smooth to varying degrees, which manifests itself in the intensity of the return signal and, accordingly, the brightness of the corresponding area in the image. thermal shooting
It is based on the detection of thermal anomalies by fixing the thermal radiation of Earth objects due to endogenous heat or solar radiation.
The infrared range of the spectrum of electromagnetic oscillations is conditionally divided into three parts (in microns): near (0.74-1.35), medium (1.35-3.50), far (3.50-1000).
Solar (external) and endogenous (internal) heat heats geological objects in different ways. IR radiation, passing through the atmosphere, is selectively absorbed, and therefore thermal photography can only be carried out in the area where the so-called "transparency windows" are located - places where IR rays are transmitted.
Empirically, four main transparency windows (in microns) were identified: 0.74-2.40; 3.40-4.20; 8.0-13.0; 30.0-80.0.
space pictures
Three main ways to transmit data from a satellite to Earth.
Direct data transmission to ground station.
The received data is stored on the satellite and then transmitted with some time delay to the Earth.
Use of the system of geostationary communication satellites TDRSS (Tracking and Data Relay Satellite System).
13. ERDAS IMAGINE delivery kits
ERDAS IMAGINE is one of the most popular geospatial software products in the world. ERDAS IMAGINE combines in powerful and user-friendly software the capabilities of processing and analyzing a variety of raster and vector geospatial information, allowing you to create products such as georeferenced images that have undergone improved transformations, orthomosaics, vegetation classification maps, flight clips in the "virtual world", vector maps obtained as a result of processing aerial and space images.
IMAGINE Essentials is an entry-level product that contains basic tools for visualization, correction, and mapping. Allows you to use batch processing.
IMAGINE Advantage includes all the features of IMAGINE Essentials. In addition, it provides advanced spectral processing, change analysis, orthocorrection, mosaic, image analysis. Allows for parallel batch processing.
IMAGINE Professional includes all the features of IMAGINE Advantage. In addition, it offers a set of advanced tools for processing spectral, hyperspectral and radar data, as well as spatial modeling. Includes ERDAS ER Mapper.
Additional modules, such as SAR Interferometry, IMAGINE Objective and others, expand the functionality of the software package, making it a universal tool for working with geospatial information.
14. Digital data. Schematic representation of converting raw data to pixel values
Digital data in the process of scanning the sensor generates an electrical signal, the intensity of which varies depending on the brightness of the area of the earth's surface. In multi-zone imaging, separate independent signals correspond to different spectral ranges. Each such signal changes continuously in time, and for further analysis it must be converted into a set of numerical values. To convert a continuous analog signal into digital form, it is divided into parts corresponding to equal sampling intervals (Figure 11). The signal within each interval is described only by the average value of its intensity; therefore, all information about signal variations in this interval is lost. Thus, the value of the sampling interval is one of the parameters on which the resolution of the sensor directly depends. It should also be noted that for digital data, not an absolute, but a relative brightness scale is usually chosen, therefore, these data do not reflect the true radiometric values obtained for a given scene.
15. Engineering system design
When designing any technogenic system, including information systems, first of all, the goals are determined, the achievement of which must be ensured, and the priority tasks to be solved during the operation of the system.
Let's define the main goal of the GIS "Caspian" project as follows: to create a multi-purpose, multi-user system of operational information services for central and local authorities, state environmental control bodies, an emergency agency and its divisions, oil and gas industry companies, as well as other official or private organizations and persons. interested in solving the territorial problems of the region.
Priority tasks can be formulated based on a brief description of the territory. In our opinion, these tasks are as follows:
mapping of natural structures and objects with analysis and description of geological, landscape and other territorial patterns;
thematic mapping of the infrastructure of the oil and gas industry with a fairly accurate reference to the topographic base and landscape, geomorphological, ecological maps of the coast;
operational control and forecast of the dynamics of the coastline with an analysis of the territorial problems that arise in this case (destruction of dams, flooding of oil wells, removal of oil spills into the sea, oil contamination of coastal areas, etc.);
tracking ice conditions, especially in shelf areas where oil is produced from offshore platforms.
Based on the list of priority tasks, we formulate the substantive requirements for the system:
at the first stage of the system implementation, use the available NOAA/AVHRR and TERRA/MODIS space facilities and, accordingly, monitor large-scale and medium-scale processes - thermal fields, ice covers, water surfaces. Provide for the possibility of developing the system using active (RADARSAT-1, 2 ERS-1) and passive (Landsat-7. SPOT-4,1RS) high-resolution surveys;
The system should provide for the reception, archiving and processing of ground-based observational data obtained both at the network of agrometeorological stations and at sub-satellite ranges and test sites. The composition of the equipment is determined depending on the problem being solved;
*Expeditionary ground and aircraft observations can also serve as an additional source of information. Depending on the equipment of these expeditions, information can be received online or after office processing.
System agreements on access to information, terms of its storage, pricing of primary and processed data, etc. should be developed jointly with interested ministries, regional and district akimats and other state consumers of monitoring data. The system design must provide for the possibility of including the appropriate control and service programs.
These basic requirements define the limits beyond which the designer has no right. However, we note that the narrower this framework, the tighter the constraints, the easier it is to design and program. Therefore, a competent designer strives for close interaction with the customer when developing technical specifications.
The expediency of creating such a system has been proven by numerous examples of the effective use of GIS in solving a variety of territorial problems. The peculiarity of this work is the design and implementation of GIS monitoring and modeling of territorial processes in the territory under consideration, taking into account the currently existing information technology infrastructure.
At the first stage, we will formulate the minimum mandatory conditions that apply to an information (or rather, to any technogenic) system to ensure its “viability”. A system can function and evolve effectively if:
its functional purpose meets the needs of the environment (as a rule, also the system) in which it is immersed;
its structure does not contradict the architecture of the systems with which it interacts;
its structure is not internally contradictory and has a high degree of flexibility and modifiability;
the procedures embedded in it are combined in an efficient way into technological chains corresponding to the general technological scheme of the system functioning;
its reduction or expansion does not lead to the destruction of the structure, and each stage of the "life cycle" of the system, each version of it is used to perform
relevant functions.
The listed conditions for the effectiveness of technogenic systems can be
illustrated with many examples. These conditions are especially clearly demonstrated by the so-called monitoring systems. Among them, a powerful monitoring system, the World Meteorological Service, is a striking example.
16. Decryption methods
When deciphering a radar aerospace image, regardless of the chosen method, it is necessary:
detect a target or terrain object in the image;
identify the target or object of the terrain;
analyze the detected target or terrain object and determine their quantitative and qualitative characteristics;
arrange the results of decoding in the form of a graphic or text document.
Depending on the conditions and place of implementation, the interpretation of radar images can be divided into field, aerial visual, cameral and combined.
Zero decryption
In field interpretation, the decoder directly on the ground is guided by characteristic and easily recognizable objects of the terrain and, comparing the contours of objects with their radar images, puts the results of identification with conventional signs on a photograph or a topographic map.
During field interpretation, along the way, by direct measurements, the numerical and qualitative characteristics of objects are determined (characteristics of vegetation, water bodies, structures adjacent to them, characteristics of settlements, etc.). At the same time, objects that were not depicted in the image due to their small size or because they did not exist at the time of shooting can be plotted on the image or map. During field interpretation, standards (keys) are specially or incidentally created, with the help of which, in the future, in office conditions, the identification of objects of the same type of terrain is facilitated.
The disadvantages of field interpretation of images are its laboriousness in terms of time and cost, and the complexity of its organization.
Aerovisual interpretation of aerospace images
Recently, in the practice of aerial photographic work, the aerovisual method of deciphering aerial photographs has been increasingly used. This method can be successfully applied in deciphering radar images of the terrain.
The essence of the aerovisual method is the identification of images of an object from an airplane or helicopter. Observation can be carried out through optical and infrared devices. Aerovisual interpretation of radar images can increase productivity and reduce the cost of field interpretation.
The data obtained as a result of the interpretation of this image will allow us to determine the location of pollution sources and assess their intensity (Fig. 12).
Cameral interpretation of aerospace images
In cameral interpretation of images, identification of objects and their interpretation is carried out without comparing images with nature, by studying images of objects according to their decoding features. Cameral interpretation of images is widely used in the preparation of contour radar maps, updating topographic maps, geological research, and when correcting and supplementing cartographic materials in hard-to-reach areas.
However, cameral interpretation has a significant drawback - it is impossible to fully obtain all the necessary information about the area. In addition, the results of cameral interpretation of images do not correspond to the time of interpretation, but to the moment of shooting. Therefore, it seems highly expedient to combine cameral and field or aerial visual interpretation of images, i.e., their combination.
With combined interpretation of images, the main work on the detection and identification of objects is carried out in office conditions, and in the field or in flight, those objects or their characteristics that cannot be identified in office are performed and identified.
Cameral decryption is divided into two methods:
direct or semi-instrumental deciphering;
instrumental decoding.
Direct decryption method
With the direct method of decoding, the performer visually, without devices or with the help of magnifying devices, examines the image and, based on the decoding features of the image and his experience, identifies and interprets the objects.
With the direct method of deciphering images, the instruments used are auxiliary, improving the conditions of observation. Some devices allow the decryptor to determine the quantitative characteristics of the decrypted objects. But the main role in detection, recognition and interpretation is played by a person.
Auxiliary devices and tools include sets of magnifiers with various magnifications, measuring scales, stereoscopes, parallax rulers, parallaxometers, special devices for interpretation, projection screens, television and electro-optical closed systems that improve the conditions for deciphering images.
17. Distortion of satellite images
Analysis of the subsystem of a real space image leads to the conclusion that the sources of distortion (noise) in satellite imagery can be represented by three subsystems of distorting factors:
errors in the operation of filming and recording equipment;
"noises" of the environment of propagation of electromagnetic radiation and features of the surface of the object of shooting;
changing media orientation while shooting.
Such a systematization makes it possible to develop a strategy for studying and correcting satellite image distortions, since it leads to the following conclusions:
the nature of the distortions caused by sources of the second and third types with minor modifications, mainly related to the spectral range used, will be the same for any imaging systems. For this reason, such distortions can be studied by abstracting to a certain extent from a specific type of filming equipment;
the nature of the distortions caused by the sources of the first group is established by a comprehensive study of the equipment, and it is necessary to develop methods for its calibration and control during operation in orbit, which should allow correcting most of the distortions caused by the imperfect functioning of the equipment.
Distorting factors can also be subdivided according to the way in which the distortions caused by this or that noise source are taken into account:
factors, the influence of which can be taken into account relatively simply and with sufficient accuracy by introducing corrections to the coordinates of points in the image, and these corrections are calculated according to final mathematical formulas;
factors, the consideration of which requires the use of modern methods of mathematical statistics and the theory of processing measurements.
In foreign publications on satellite imagery, these subsystems of distorting factors are called predictable and measurable, respectively, i.e., requiring measurements and mathematical and statistical processing of their results.
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presentation, added 02/19/2011
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collection of information about an object or phenomenon using a recording device that is not in direct contact with this object or phenomenon. The term "remote sensing" usually includes the registration (recording) of electromagnetic radiation through various cameras, scanners, microwave receivers, radars and other devices of this kind. Remote sensing is used to collect and record information about the seabed, the Earth's atmosphere, and the solar system. It is carried out using ships, aircraft, spacecraft and ground-based telescopes. Field-oriented sciences such as geology, forestry and geography also commonly use remote sensing to collect data for their research. see also COMMUNICATION SATELLITE; ELECTROMAGNETIC RADIATION.
Bursha M. Fundamentals of space geodesy. M., 1971–1975
Remote sensing in meteorology, oceanology and hydrology. M., 1984
Seybold E., Berger W. Ocean floor. M., 1984
Mishev D. Remote sensing of the Earth from space. M., 1985
To find " REMOTE SENSING" on the
Obtaining and processing data for GIS is the most important and time-consuming step in the creation of such information systems. At present, the method of obtaining data on objects based on remote sensing data (ERS) and GPS measurements is considered the most promising and economically feasible.
In a broad sense, remote sensing is the receipt by any non-contact methods of information about the surface of the Earth, objects on it or in its depths. Traditionally, remote sensing data includes only those methods that make it possible to obtain an image of the earth's surface from space or from the air in any part of the electromagnetic spectrum.
There are several types of imaging that use the specific properties of radiation with different wavelengths. When conducting a geographic analysis, in addition to the remote sensing itself, spatial data from other sources are necessarily used - digital topographic and thematic maps, infrastructure schemes, external databases. Images allow not only to identify various phenomena and objects, but also to evaluate them quantitatively.
The advantages of the method of remote sensing of the Earth are as follows:
Relevance of data at the time of survey (most cartographic materials are hopelessly outdated);
High efficiency of data acquisition;
High accuracy of data processing due to the use of GPS technologies;
High information content (the use of spectral-zonal, infrared and radar imaging allows you to see details that are not distinguishable in ordinary images);
Economic feasibility (the cost of obtaining information through remote sensing is significantly lower than ground field work);
The ability to obtain a three-dimensional terrain model (relief matrix) through the use of stereo mode or lidar sounding methods and, as a result, the ability to conduct three-dimensional modeling of a section of the earth's surface (virtual reality systems).
Remote methods are characterized by the fact that the recording device is significantly removed from the object under study. In such studies of phenomena and processes on the earth's surface, distances to objects can be measured from units to thousands of kilometers. This circumstance provides the necessary overview of the surface and allows obtaining the most generalized images.
There are various classifications of remote sensing. Let's note the most important from the point of view of practical data collection in the oil and gas industry.
Self-radiation of objects and reflected radiation of other sources can be registered. These sources can be the Sun or the imaging equipment itself. In the latter case, coherent radiation (radar, sonars, and lasers) is used, which makes it possible to record not only the radiation intensity, but also its polarization, phase, and Doppler shift, which provides additional information. It is clear that the operation of self-emitting (active) sensors does not depend on the time of day, but it requires a significant amount of energy. Thus, the types of sounding by signal source:
Active (stimulated emission of objects initiated by an artificial source of directional action);
Passive (intrinsic, natural reflected or secondary thermal radiation of objects on the Earth's surface due to solar activity).
Filming equipment can be placed on various platforms. The platform can be a spacecraft (SC, satellite), an airplane, a helicopter, and even a simple tripod. In the latter case, we are dealing with ground-based surveys of the sides of objects (for example, for architectural and restoration tasks) or oblique surveys from natural or artificial high-altitude objects. The third type of platform is not considered due to the fact that it belongs to specialties that are far from the one for which these lectures were written.
One platform can accommodate several imaging devices, called instruments or sensors, which is common for spacecraft. For example, Resurs-O1 satellites carry MSU-E and MSU-SK sensors, and SPOT satellites carry two identical HRV sensors (SPOT-4 - HRVIR). It is clear that the farther the platform with the sensor is from the object under study, the greater the coverage and the less detail the resulting images will have.
Therefore, at present, the following types of surveys are distinguished for obtaining remote sensing data:
1. Space shooting (photographic or optoelectronic):
Panchromatic (more often in one wide visible part of the spectrum) - the simplest example is black and white photography;
Color (shooting in several, more often real colors on one media);
Multizone (simultaneous, but separate image fixation in different zones of the spectrum);
Radar (radar);
2. Aerial photography (photographic or optical-electronic):
The same types of remote sensing as in space photography;
Lidar (laser).
Both types of surveys are widely used in the oil and gas industry when creating an enterprise GIS, while each of them occupies its own niche. Space imagery (CS) has a lower resolution (from 30 to 1 m, depending on the type of survey and type of spacecraft), but due to this it covers large areas. Satellite imagery is used to survey large areas in order to obtain operational and up-to-date information about the area of proposed geological exploration, the basic basis for creating a global GIS for the mining area, environmental monitoring of oil spills, etc. In this case, both ordinary monochrome (black-and-white shooting) and spectral zonal are used.
Aerial photography (AFS), allows you to get a higher resolution image (from 1-2 m to 5-7 cm). Aerial photography is used to obtain highly detailed materials for solving the problems of the land cadastre in relation to the leased areas of mining, accounting and property management. In addition, the use of aerial photography today seems to be the best option for obtaining data for creating a GIS for linearly extended objects (oil, gas pipelines, etc.) due to the possibility of using a "corridor" survey.
The characteristics of the resulting images (both APS and CS), i.e. the ability to detect and measure a particular phenomenon, object or process depends on the characteristics of the sensors, respectively. The main characteristic is the resolution.
Remote sensing systems are characterized by several types of resolutions: spatial, spectral, radiometric and temporal. The term "resolution" usually refers to spatial resolution.
Spatial resolution (Figure 1) characterizes the size of the smallest objects visible in the image. Depending on the tasks to be solved, data of low (more than 100 m), medium (10 - 100 m) and high (less than 10 m) resolutions can be used. Images of low spatial resolution are general and allow one-time coverage of large areas - up to the whole hemisphere. Such data are used most often in meteorology, in monitoring forest fires and other large-scale natural disasters. Today, images of medium spatial resolution are the main source of data for monitoring the natural environment. Satellites with imaging equipment operating in this range of spatial resolutions have been launched and are being launched by many countries - Russia, the USA, France, etc., which ensures the constancy and continuity of observation. Until recently, high-resolution surveys from space were carried out almost exclusively in the interests of military intelligence, and from the air - for the purpose of topographic mapping. However, today there are already several commercially available high-resolution space sensors (KVR-1000, IRS, IKONOS) that make it possible to conduct spatial analysis with greater accuracy or refine analysis results at medium or low resolution.
Spectral resolution indicates which parts of the spectrum of electromagnetic waves (EMW) are recorded by the sensor. When analyzing the natural environment, for example, for environmental monitoring, this parameter is the most important. Conventionally, the entire range of wavelengths used in remote sensing can be divided into three sections - radio waves, thermal radiation (IR radiation) and visible light. This division is due to the difference in the interaction of electromagnetic waves and the earth's surface, the difference in the processes that determine the reflection and radiation of EMW.
The most commonly used EMW range is visible light and short-wave infrared radiation adjacent to it. In this range, reflected solar radiation carries information mainly about the chemical composition of the surface. Just as the human eye distinguishes substances by color, a remote sensing sensor captures “color” in the broader sense of the word. While the human eye registers only three sections (zones) of the electromagnetic spectrum, modern sensors are able to distinguish between tens and hundreds of such zones, which makes it possible to reliably detect objects and phenomena from their previously known spectrograms. For many practical problems, such detail is not always needed. If the objects of interest are known in advance, a small number of spectral zones can be selected in which they will be most noticeable. So, for example, the near infrared range is very effective in assessing the state of vegetation, determining the degree of its inhibition. For most applications, a sufficient amount of information is provided by multi-zone imaging from LANDSAT (USA), SPOT (France), Resurs-O (Russia) satellites. Sunlight and clear weather are essential for successful imaging in this wavelength range.
Typically, optical imaging is carried out either immediately in the entire visible range (panchromatic), or in several narrower zones of the spectrum (multizonal). Ceteris paribus, panchromatic images have a higher spatial resolution. They are most suitable for topographic tasks and for clarifying the boundaries of objects identified on multi-zone images of lower spatial resolution.
Thermal IR radiation (Figure 2) carries information mainly about the surface temperature. In addition to the direct determination of the temperature regimes of visible objects and phenomena (both natural and artificial), thermal images make it possible to indirectly reveal what is hidden underground - underground rivers, pipelines, etc. Since thermal radiation is created by the objects themselves, sunlight is not required to take pictures (it is even more likely to interfere). Such images make it possible to track the dynamics of forest fires, oil and gas flares, and underground erosion processes. It should be noted that it is technically difficult to obtain space thermal images of high spatial resolution, therefore images with a resolution of about 100 m are available today. Thermal photography from aircraft also provides a lot of useful information.
The centimeter range of radio waves is used for radar surveys. The most important advantage of images of this class is their all-weather capability. Since the radar registers its own radiation reflected by the earth's surface, it does not require solar
light. In addition, radio waves of this range freely pass through continuous clouds and are even able to penetrate to a certain depth into the soil. The reflection of centimeter radio waves from the surface is determined by its texture (“roughness”) and the presence of various films on it. So, for example, radars are able to detect the presence of an oil film 50 microns thick or more on the surface of water bodies even with significant waves. In principle, radar surveys from aircraft are capable of detecting underground objects such as pipelines and leaks from them.
Radiometric resolution determines the range of brightness that can be seen in an image. Most sensors have a radiometric resolution of 6 or 8 bits, which is closest to the instantaneous dynamic range of human vision. But there are sensors with a higher radiometric resolution (10 bits for AVHRR and 11 bits for IKONOS), which allows you to see more details in very bright or very dark areas of the image. This is important when shooting objects that are in the shade, as well as when the image contains large water surfaces and land at the same time. In addition, sensors such as the AVHRR are radiometrically calibrated, allowing for accurate quantitative measurements.
Finally, the temporal resolution determines how often the same sensor can capture a certain area of the earth's surface. This parameter is very important for monitoring emergencies and other rapidly developing phenomena. Most satellites (more precisely, their families) provide re-imaging after a few days, some - after a few hours. In critical cases, images from various satellites can be used for daily observation, however, it must be borne in mind that ordering and delivery in themselves can take a considerable amount of time. One solution is to purchase a receiving station that allows you to receive data directly from the satellite. This convenient solution for continuous monitoring is used by some organizations in Russia that have data receiving stations from Resurs-O satellites. To track changes in any territory, the possibility of obtaining archival (retrospective) images is also important.
Height satellite orbits can be divided into three groups: 1) low heights: 100-500 km (manned ships and orbital stations); 2) Average Heights: 500-2000 km (resource and meteorological satellites); 3) Great Heights: 36000-40000 km (geostationary satellites - the speed of the satellite is equal to the speed of the Earth's rotation - constant monitoring of a certain area on the surface).
The position of the orbit relative to the Sun. For space surveys, the ability of the orbit to maintain a constant orientation to the Sun is of great importance. Orbits in which the angle between the plane of the orbit and the direction to the Sun remains constant are called sun-synchronous. The advantage of such orbits is that they provide the same illumination of the earth's surface along the flight path of the spacecraft.
B.A. Dvorkin, S.A. Dudkin
Revolutionary development of computer, space, information technologies in the late XX - early XXI centuries. led to qualitative changes in the industry of remote sensing of the Earth (ERS): spacecraft with new generation imaging systems have appeared that allow obtaining images with ultra-high spatial resolution (up to 41 cm for the GeoEye-1 satellite). Filming is carried out in hyperspectral and multichannel multispectral (currently up to 8 channels on the WorldView-2 satellite) modes. The main trends of recent years are the emergence of new ultra-high-resolution satellites with improved characteristics (French Pleiades system), the development of a concept for operational and global high-resolution imaging of the earth's surface using constellations of small satellites (the German RapidEye constellation, replenishment of the DMC constellation with a high-resolution satellite, advanced satellites SkySat, NovaSAR, etc.). In remote sensing technologies, in addition to traditional areas (improving spatial resolution, adding new spectral channels, automating processing processes and prompt data provision), there are developments related to operational video recording of objects from space (for example, developments by SkyBox Imaging, USA).
In this review, we will characterize some of the most interesting high and ultra-high resolution remote sensing satellites launched into orbit over the past two years and planned to be launched in the next 3–4 years.
RUSSIA
In accordance with the Federal Space Program in 2012, a small spacecraft (SC) was launched "Kanopus-V". It is designed to provide departments of Roscosmos, the Russian Emergencies Ministry, the Russian Ministry of Natural Resources, Roshydromet, the Russian Academy of Sciences and other interested departments with operational information. Among the tasks facing the satellite are:
- detection of forest fires, large emissions of pollutants into the environment;
- monitoring of man-made and natural emergencies, including natural hydrometeorological phenomena;
- monitoring of agricultural activities, natural (including water and coastal) resources;
- land use;
- operational observation of specified areas of the earth's surface .
A sample image from the Kanopus-V spacecraft is shown in fig. one.
Main characteristicsKA "Kanopus-V"
KA "Kanopus-V"
In addition to the Kanopus-V satellite, the Resurs-DK1 (launched in 2006) and Monitor-E (launched in 2005) satellites are currently being completed as part of the Russian orbital remote sensing constellation. Features of the Resurs-DK1 spacecraft are increased operational and accuracy characteristics of the obtained images (resolution 1 m in panchromatic mode, 2–3 m in multispectral mode). Satellite data is actively used to create and update topographic and special maps, information support for rational nature management and economic activity, inventory of forests and agricultural land, and other tasks.
Optoelectronic spacecraft will be a continuation of the mission of domestic high-resolution natural resource satellites "Resource-P", which is scheduled for launch in 2013. When creating the satellite, technical solutions developed during the creation of the Resurs-DK1 spacecraft are used. The use of a circular sun-synchronous orbit with a height of 475 km will significantly improve the observation conditions. From six to three days, the frequency of observation will improve. Shooting will be conducted in panchromatic and 5-channel multispectral modes. In addition to high-resolution optical-electronic equipment, the satellite will be equipped with a hyperspectral spectrometer (HSA) and a wide-angle multispectral imaging complex of high (SHMSA-VR) and medium (SHMSA-SR) resolution (SHMSA-SR).
The main characteristics of the spacecraft "Resurs-P"
In the near future, the Russian orbital constellation of remote sensing is planned to be expanded with the launch of satellites of the Obzor series.
Grouping of four optical-electronic spacecraft "Obzor-O" is designed for operational multispectral imaging of Russia, adjacent territories of neighboring states and individual regions of the Earth. At the 1st stage (2015–2017), it is planned to launch two spacecraft, at the 2nd stage (2018–2019) - two more. The Obzor-O system will serve to provide satellite imagery data to the Russian Ministry of Emergency Situations, the Russian Ministry of Agriculture, the Russian Academy of Sciences, Rosreestr, other ministries and departments, as well as regions of Russia. It is planned to install prototypes of hyperspectral equipment on Obzor-O spacecraft No. 1 and No. 2.
The main characteristics of the spacecraft "Obzor-O"
The main technical characteristics of the survey equipment of the spacecraft Obzor-O
| Shooting mode | multispectral | ||
| Stage 1 | Stage 2 | ||
| spectral range, micron | 7 simultaneous spectral channels: | 8 simultaneous spectral channels: | |
| m | no more than 7 (for channel 0.50–0.85); no more than 14 (for other channels) | no more than 5 (for channel 0.50–0.85); no more than 20 (for channel 0.55–1.70); no more than 14 (for other channels) | |
| radiometric resolution, bits per pixel | 12 | ||
| m | 30–45 | 20–40 | |
| Shooting bandwidth, km | at least 85 | at least 120 | |
| Capture performance of each spacecraft, million sq. km/day | 6 | 8 | |
| shooting frequency, day | 30 | 7 | |
| Mbps | 600 | ||
radar spacecraft "Obzor-R" is designed for shooting in the X-band at any time of the day (regardless of weather conditions) in the interests of the socio-economic development of the Russian Federation. Obzor-R will serve to provide radar survey data to the Russian Ministry of Emergency Situations, the Russian Ministry of Agriculture, Rosreestr, other ministries and departments, as well as regions of Russia.
The main characteristics of the spacecraft"Obzor-R"
"Obzor-R"
| Spectral range | X-band (3.1cm) | |||
| shooting frequency, day | 2 (in the latitude band from 35 to 60°N) | |||
| Mode | m | line of sight, km | Shooting bandwidth, km | Polarization |
| High Detail Frame Mode (VDC) | 1 | 2×470 | 10 | Single (optional - H/H, V/V, H/V, V/H) |
| Detailed frame mode (DC) | 3 | 2×600 | 50 | Single (optional - H/H, V/V, H/V, V/H); double (optional - V/(V+H) and H/(V+H)) |
| Narrow Band Route Mode (BM) | 5 | 2×600 | 30 | |
| 3 | 2×470 | |||
| Route mode | 20 | 2×600 | 130 | |
| 40 | 230 | |||
| Broadband route mode | 200 | 2×600 | 400 | |
| 300 | 600 | |||
| 500 | 2×750 | 750 | ||
BELARUS
Launched in 2012 together with the Russian Kanopus-V satellite BKA(Belarusian spacecraft), provides full coverage of the country's territory with satellite imagery. According to the international classification, the spacecraft belongs to the class of small satellites (it is completely identical to the Kanopus-V spacecraft). The payload of the SKA includes panchromatic and multispectral cameras with a capture bandwidth of 20 km. The resulting images allow viewing objects on the earth's surface with a resolution of 2.1 m in panchromatic mode and 10.5 m in multispectral mode. This is sufficient to carry out various monitoring tasks, such as identifying fires, etc. However, in the future, the country may need a satellite with a higher resolution. Belarusian scientists are ready to start developing a spacecraft with a resolution of up to 0.5 m. The final decision on the project of the new satellite will apparently be made in 2014, and its launch can be expected no earlier than 2017.
UKRAINE
SC launch "Sich-2" was carried out within the framework of the national space program of Ukraine in order to further develop the system of space monitoring and geoinformation support for the national economy of the country. The satellite is equipped with an optical-electronic sensor with three spectral and one panchromatic channels, as well as a mid-infrared scanner and the Potential scientific equipment complex. Among the main tasks facing the Sich-2 mission are: monitoring of agricultural and land resources, water bodies, the state of forest vegetation, control of emergency areas. A sample image from the Sich-2 spacecraft is shown in fig. 2.
Main characteristicsKA "Sich-2"
| Launch Date: August 17, 2011 | ||
| Launch vehicle: RN "Dnepr" | ||
| Developer: GKB "Southern" them. M.K. Yangel | ||
| Operator: State Space Agency of Ukraine | ||
| Mass of spacecraft, kg | 176 | |
| Orbit | Type | Sun-synchronous |
| Height, km | 700 | |
| Mood, deg. | 98,2 | |
| years | 5 | |
Main technical characteristics of filming equipmentKA "Sich-2"
The State Space Agency of Ukraine plans to launch the Sich-3-O spacecraft with a resolution better than 1 m in the near future. The satellite is being created at Yuzhnoye Design Bureau.
In the US, the remote sensing industry is actively developing, primarily in the ultra-high resolution sector. On February 1, 2013, two leading American companies DigitalGlobe and GeoEye, the world leaders in the field of supplying ultra-high resolution data, united. The new company retained the name DigitalGlobe. The total market value of the company is $2.1 billion.
As a result of the merger, DigitalGlobe is now uniquely positioned to provide a wide range of satellite imagery and geographic information services. Despite the monopoly position in the most profitable segment of the market, the main part of the income (75-80%) of the combined company comes from a defense order under the 10-year EnhanctdView (EV) program worth $7.35 billion, which provides for the state procurement of commercial satellite resources in the interests of the National geospatial intelligence agency (NGA).
At present, DigitalGlobe is the operator of the WorldView-1 (resolution - 50 cm), WorldView-2 (46 cm), QuickBird (61 cm), GeoEye-1 (41 cm) and IKONOS (1 m) ultra-high resolution remote sensing satellites. The total daily performance of the system is more than 3 million square meters. km.
In 2010, DigitalGlobe entered into a contract with Ball Aerospace to develop, build and launch a satellite WorldView-3. The contract is valued at $180.6 million. Exelis VIS was awarded a $120.5 million contract to build an onboard imaging system for the WorldView-3 satellite. The WorldView-3 imaging system will be similar to that installed on the WoldView-2 spacecraft. In addition, shooting will be carried out in SWIR (8 channels; 3.7 m resolution) and CAVIS (12 channels; 30 m resolution) modes.
The main characteristics of the spacecraftWorldView-3
Main technical characteristics of spacecraft imaging equipmentWorldView-3
| Shooting mode | Panchromatic | multispectral |
| spectral range, micron | 0,50–0,90 | 0.40–0.45 (purple or coastal) 0.45-0.51(blue) 0.51–0.58 (green) 0.585–0.625 (yellow) 0.63–0.69 (red) 0.63–0.69 (extreme red or red-edge) 0.77–0.895 (near IR-1) 0.86–1.04 (near IR-2) |
| Spatial resolution (in nadir), m | 0,31 | 1,24 |
| hail | 40 | |
| radiometric resolution, bits per pixel | 11 | |
| Geolocation accuracy, m | CE90 mono = 3.5 | |
| Shooting bandwidth, km | 13,1 | |
| shooting frequency, day | 1 | |
| Yes | ||
| File Format | GeoTIFF, NITF | |
Promising spacecraft GeoEye-2 began to be developed in 2007. It will have the following specifications: resolution in panchromatic mode - 0.25–0.3 m, improved spectral characteristics. The sensor manufacturer is Exelis VIS. Initially, the launch of the satellite was planned in 2013, however, after the merger of DigitalGlobe and GeoEye, it was decided to complete the creation of the satellite, put it in storage for the subsequent replacement of one of the satellites in orbit, or until the moment when demand makes its launch profitable for the company.
On February 11, 2013, a new spacecraft was launched Landsat-8(LDCM project - Landsat Data Continuity Mission). The satellite will continue to replenish the bank of images obtained with the help of Landsat satellites for 40 years and covering the entire surface of the Earth. Two sensors are installed on the Landsat-8 spacecraft: optoelectronic (Operational Land Imager, OLI) and thermal (Thermal InfraRed Sensor, TIRS).
The main characteristics of the spacecraftLandsat-8
| Launch date February 11, 2013 | ||
| Launch site: Vandenberg Air Force Base | ||
| Launch vehicle: RN Atlas 5 | ||
| Developer: Orbital Sciences Corporation (OSC) (formerly General Dynamics Advanced Information Systems) (platform); Ball Aerospace (payload) | ||
| Operators: NASA and USGS | ||
| Weight, kg | 2623 | |
| Orbit | Type | Sun-synchronous |
| Height, km | 705 | |
| Mood, deg. | 98,2 | |
| Estimated period of operation, years | 5 | |
Main technical characteristics of spacecraft imaging equipmentLandsat-8
FRANCE
In France, the main commercial operator of remote sensing satellites is Astrium GEO-Information Services, a geoinformation division of the international company Astrium Services. The company was founded in 2008 as a result of the merger of the French company SpotImage and the Infoterra group of companies. Astrium Services-GEO-Information is the operator of SPOT and Pleiades high and ultra-high resolution optical satellites, TerraSAR-X and TanDEM-X new generation radar satellites. Astrium Services-GEO-Information is headquartered in Toulouse and has 20 offices and more than 100 distributors worldwide. Astrium Services is part of the European Aeronautic Defense and Space Company (EADS).
The SPOT (Satellite Pour L'Observation de la Terre) satellite system for observing the Earth's surface was designed by the French National Space Agency (CNES) together with Belgium and Sweden. The SPOT system includes a number of spacecraft and ground facilities. The satellites currently in orbit are SPOT-5 (launched in 2002) and SPOT-6(launched in 2012; Fig. 3). The SPOT-4 satellite was decommissioned in January 2013. SPOT-7 it is planned to launch in 2014. SPOT-6 and SPOT-7 satellites have identical characteristics.
The main characteristics of the spacecraftSPOT-6 and SPOT-7
Main technical characteristics of spacecraft imaging equipmentSPOT-6 and SPOT-7
Launched in 2011-2012 KA Pleiades-1A and Pleiades-1B(Fig. 4), France launched an ultra-high-resolution Earth imaging program in competition with American commercial remote sensing systems.
The Pleiades High Resolution program is an integral part of the European remote sensing satellite system and has been led by the French space agency CNES since 2001.
The Pleiades-1A and Pleiades-1B satellites are synchronized in the same orbit in such a way as to be able to provide daily imagery of the same area of the earth's surface. Using next-generation space technologies such as fiber-optic gyro stabilization systems, spacecraft equipped with state-of-the-art systems have unprecedented maneuverability. They can survey anywhere in the 800 km strip in less than 25 seconds with a geolocation accuracy of less than 3 m (CE90) without using ground control points and 1 m using ground points. Satellites are capable of capturing more than 1 million sq. km per day in panchromatic and multispectral modes.
The main characteristics of the spacecraftPleiades-1A and Pleiades-1B
Main technical characteristics of filming equipmentPleiades-1A and Pleiades-1B
| Shooting mode | Panchromatic | multispectral |
| spectral range, micron | 0,48–0,83 | 0.43–0.55 (blue) 0.49–0.61 (green) 0.60–0.72 (red) 0.79 - 0.95 (near IR) |
| Spatial resolution (in nadir), m | 0.7 (after processing - 0.5) | 2.8 (after processing - 2) |
| Maximum deviation from nadir, hail | 50 | |
| Geolocation accuracy, m | CE90=4.5 | |
| Shooting bandwidth, km | 20 | |
| shooting performance, million sq. km/day | more than 1 | |
| shooting frequency, day | 1 (depending on the latitude of the shooting area) | |
| File Format | GeoTIFF | |
| Data transfer rate to the ground segment, Mbps | 450 | |
JAPAN
The most famous Japanese remote sensing satellite was ALOS (optical-electronic survey with a resolution of 2.5 m in panchromatic mode and 10 m in multispectral mode, as well as radar survey in the L-band with a resolution of 12.5 m). The ALOS spacecraft was created as part of the Japanese space program and is funded by the Japanese space agency JAXA (Japan Aerospace Exploration Agency).
The ALOS spacecraft was launched in 2006, and on April 22, 2011, problems arose with the control of the satellite. After three weeks of unsuccessful attempts to restore the operation of the spacecraft, on May 12, 2011, the command was given to turn off the power to the satellite equipment. Currently only archival images are available.
The ALOS satellite will be replaced by two spacecraft at once - one optical-electronic, the second - radar. Thus, the JAXA agency specialists refused to combine optical and radar systems on one platform, which was implemented on the ALOS satellite, on which two optical cameras (PRISM and AVNIR) and one radar (PALSAR) are installed.
radar spacecraft ALOS-2 scheduled for launch in 2013
The main characteristics of the spacecraft ALOS-2
Main technical characteristics of spacecraft imaging equipment ALOS-2
Launch of optoelectronic spacecraft ALOS-3 planned for 2014. It will be capable of panchromatic, multispectral and hyperspectral imaging.
Main characteristicsKAALOS-3
Main technical characteristics of filming equipmentKAALOS-3
The Japanese project ASNARO (Advanced Satellite with New system ARchitecture for Observation), which was initiated by USEF (Institute for Unmanned Space Experiment Free Flyer) in 2008, should also be noted. The project is based on innovative technologies for creating mini-satellite platforms (weighing 100–500 kg) and filming systems. One of the goals of the ASNARO project is to create a new generation ultra-high-resolution mini-satellite that could compete with satellites of other countries with similar characteristics due to cheaper data and the ability to design and manufacture devices in a shorter time. Satellite ASNARO designed to survey the earth's surface in the interests of government organizations in Japan and is scheduled for launch in 2013.
The main characteristics of the spacecraftASNARO
Main technical characteristics of spacecraft imaging equipmentASNARO
INDIA
One of the most effective remote sensing programs has been created in the country on the basis of a planned system of state financing of the space industry. India successfully operates a constellation of spacecraft for various purposes, including the KA RESOURCESAT and СARTOSAT series.
In addition to the satellites already operating in orbit, a spacecraft was launched in April 2011 RESOURCESAT-2, designed to solve the problems of preventing natural disasters, managing water and land resources (Fig. 5).
The main characteristics of the spacecraftRESOURCESAT-2
On April 26, 2012, the spacecraft was launched RISAT-1 with a multifunctional C-band radar (5.35 GHz). The satellite is designed for round-the-clock and all-weather imaging of the Earth in various modes. Survey of the earth's surface is carried out in the C-range of wavelengths with variable polarization of radiation (HH, VH, HV, VV).
The main characteristics of the spacecraftRISAT-1
Main technical characteristics of spacecraft imaging equipmentRISAT-1
| Spectral range | C-band | |||
| Mode | Nominal spatial resolution, m | Survey strip width, km | Shooting angle range, deg. | Polarization |
| Ultra High Resolution (High Resolution SpotLight - HRS) | <2 | 10 | 20–49 | Single |
| high definition (Fine Resolution Stripmap-1 - FRS-1) |
3 | 30 | 20–49 | |
| high definition (Fine Resolution Stripmap-2 - FRS-2) |
6 | 30 | 20–49 | quadruple |
| Medium Resolution / Low Resolution (Medium Resolution ScanSAR-MRS / Coarse Resolution ScanSAR - CRS) | 25/50 | 120/240 | 20–49 | Single |
A constellation of optical-electronic spacecraft of the CARTOSAT cartographic series is operating in orbit. The next satellite of the CARTOSAT-3 series is planned to be launched in 2014. It will be equipped with optical-electronic equipment with an unprecedented spatial resolution of 25 cm.
CHINA
China over the past 6 years has created a multi-purpose orbital constellation of remote sensing satellites, consisting of several space systems - satellites for specific reconnaissance, as well as designed for oceanography, cartography, monitoring of natural resources and emergency situations.
In 2011, China launched more remote sensing satellites than other countries: two Yaogan (YG)-12 surveillance satellites (with a submeter resolution optoelectronic system) and Yaogan (YG)-13 (with a synthetic aperture radar); KA Hai Yang (HY) - 2A with a microwave radiometer lkx for solving oceanographic problems; Zi Yuan (ZY) - 1-02C multi-purpose natural resource monitoring satellite for the Ministry of Land and Natural Resources (resolution 2.3 m in panchromatic mode and 5/10 m in multispectral mode in a survey strip 54 km and 60 km wide); optical micro-satellite (35 kg) TianXun (TX) with a resolution of 30 m.
In 2012, China again became the leader in terms of the number of launches - the national remote sensing constellation (not counting meteorological satellites) was replenished with five more satellites: Yaogan (YG) - 14 and Yaogan (YG) -15 (species reconnaissance), Zi Yuan (ZY) - 3 and Tian Hui (TH) - 2 (mapping satellites), Huan Jing (HJ) radar - 1C.
spacecraft TH-1 and TH-2- the first Chinese satellites that can receive stereo images in the form of a triplet for geodetic measurements and cartographic work. They are identical in their technical characteristics and work according to a single program. Each satellite is equipped with three cameras - a stereo triplet stereo camera, a high-resolution panchromatic camera and a multispectral camera - that can capture the entire earth's surface for scientific research, land monitoring, geodesy and cartography.
Satellites are designed to solve many problems:
- creating and updating topographic maps;
- creation of digital elevation models;
- creation of 3D models;
- monitoring landscape changes;
- land use monitoring;
- monitoring the state of agricultural crops, predicting yields;
- monitoring of forest management and monitoring of the state of forests;
- monitoring of irrigation facilities;
- water quality monitoring;
The main characteristics of spacecraft
| Launch dates | August 24, 2010 (TH-1), May 6, 2012 (TH-2) | ||
| launcher | CZ-2D | ||
| Developer | China Aerospace Science and Technology Corporation, Chinese Academy of Space Technology (CAST) | ||
| Operator: Beijing Space Eye Innovation Technology Company (BSEI) | |||
| Weight, kg | 1000 | ||
| Orbit | Type | Sun-synchronous | |
| Height, km | 500 | ||
| Mood, deg. | 97,3 | ||
| Estimated period of operation, years | 3 | ||
Main technical characteristics of filming equipment
| Shooting mode | Panchromatic | multispectral | Stereo (triplet) | |
| spectral range, micron | 0,51–0,69 | 0.43–0.52 (blue) 0.52–0.61 (green) 0.61–0.69 (red) 0.76-0.90 (near IR) |
0,51–0,69 | |
| Spatial resolution (in nadir), m | 2 | 10 | 5 | |
| Geolocation accuracy, m | CE90=25 | |||
| Shooting bandwidth, km | 60 | 60 | 60 | |
| shooting frequency, day | 9 | |||
| The possibility of obtaining a stereo pair | Yes | |||
CANADA
On January 9, 2013, MDA announced that it had signed a $706 million contract with the Canadian Space Agency to build and launch a constellation of three radar satellites. RADARSAT Constellation Mission (RCM). The term of the contract is 7 years.
The RCM constellation will provide round-the-clock radar coverage of the country's territory. The data can include repeated images of the same areas at different times of the day, which will greatly improve the monitoring of coastal zones, areas of northern, Arctic waterways and other areas of strategic and defense interests. The RCM system will also include a set of automated image interpretation, which, combined with the rapid acquisition of data, will immediately detect and identify ships across the world's oceans. A significant acceleration of data processing is expected - customers will receive the necessary information almost in real time.
The RCM constellation will survey the earth's surface in the C-band (5.6 cm), with variable polarization of radiation (HH, VH, HV, VV).
The main characteristics of RCM spacecraft
Main technical characteristics of RCM spacecraft imaging equipment
| Spectral range | C-band (5.6 cm) | |||
| shooting frequency, day | 12 | |||
| Mode | Nominal spatial resolution, m | Shooting bandwidth, km | shooting angle range, deg. | Polarization |
| Low Resolution | 100 x 100 | 500 | 19–54 | Single (optional - HH or VV or HV or VH); double (optional - HH/HV or VV/VH) |
| Medium resolution (Medium Resolution - Maritime) | 50 x 50 | 350 | 19–58 | |
| 16 x 16 | 30 | 20–47 | ||
| Medium resolution (Medium Resolution - Land) | 30 x 30 | 125 | 21–47 | |
| High resolution (High Resolution) | 5 x 5 | 30 | 19–54 | |
| Super High Resolution (Very High Resolution) | 3 x 3 | 20 | 18–54 | |
| Ice/Oil Low Noise mode | 100 x 100 | 350 | 19–58 | |
| Ship Detection Mode | Other | 350 | 19–58 | |
KOREA
Since the beginning of work on the implementation of the space program in 1992, a national remote sensing system has been created in the Republic of Korea. The Korea Aerospace Research Institute (KARI) has developed a series of KOMPSAT (Korean Multi-Purpose Satellite) earth observation satellites. The KOMPSAT-1 spacecraft was used for military purposes until the end of 2007. In 2006, the KOMPSAT-2 satellite was launched into orbit.
Spacecraft launched in 2012 KOMPSAT-3 is a continuation of the KOMPSAT mission and is designed to obtain digital images of the earth's surface with a spatial resolution of 0.7 m in panchromatic mode and 2.8 m in multispectral mode.
Main characteristicsKA KOMPSAT-3
Main technical characteristics of filming equipmentKA KOMPSAT-3
The KOMPSAT-5 project is part of the Korean National Development Plan MEST (Ministry of Education, Science and Technology), which started in 2005. KA KOMPSAT-5 the Korea Aerospace Research Institute (KARI) is also being developed. The main task of the future mission is to create a radar satellite system for solving monitoring problems. Survey of the earth's surface will be carried out in the C-band with variable polarization of radiation (HH, VH, HV, VV).
The main characteristics of the spacecraftKOMPSAT-5
| Launch date: 2013 (planned) | ||
| Launch pad: Yasny launch base (Russia) | ||
| Launch vehicle: Dnepr launch vehicle (Russia) | ||
| Developer: KARI (Korea Aerospace Research Institute), Thales Alenia Space (Italy; airborne radar imaging system - SAR) | ||
| Operator: KARI | ||
| Weight, kg | 1400 | |
| Orbit | Type | Sun-synchronous |
| Height, km | 550 | |
| Inclination, deg. | 97,6 | |
| Estimated period of operation, years | 5 | |
Main technical characteristics of filming equipmentKOMPSAT-5
UNITED KINGDOM
The British company DMC International Imaging Ltd (DMCii) is the operator of the Disaster Monitoring Constellation (DMC) satellite constellation and works both in the interests of the governments of the countries that own the satellites and supplies space images for commercial use.
The DMC constellation provides real time coverage of disaster areas for government agencies and commercial use. The satellites are also shooting for solving the problems of agriculture, forestry, etc. and includes 8 mini remote sensing satellites belonging to Algeria, Great Britain, Spain, China and Nigeria. The satellite developer is the British company Surrey Satellite Technology Ltd (SSTL). All satellites are in sun-synchronous orbit to provide daily global coverage.
The British satellite UK-DMC-2, part of the DMC constellation, was launched in 2009. It is surveying in a multispectral mode with a resolution of 22 m in a 660 m wide band. Three new satellites are scheduled to be launched in 2014 DMC-3a, b, c with improved features. They will survey in a 23 km wide band with a resolution of 1 m in panchromatic mode and 4 m in 4-channel multispectral mode (including infrared channel).
SSTL is currently completing the development of a new budget radar satellite: a 400-kilogram SC NovaSAR-S will be the SSTL-300 platform with an innovative S-band radar. SSTL's approach to engineering and design allows the NovaSAR-S mission to be fully deployed within 24 months of order.
NovaSAR-S will conduct radar surveys in four modes with a resolution of 6-30 m in various polarization combinations. The technical parameters of the satellite are optimized for a wide range of applications, including flood monitoring, crop assessment, forest monitoring, land cover classification, disaster management and marine surveillance, such as ship tracking, oil spill detection.
SPAIN
A national Spanish constellation of remote sensing satellites is being formed. In July 2009, the Deimos-1 satellite, which is part of the international DMC constellation, was launched into orbit. It captures in a multispectral mode with a resolution of 22 m in a 660 m wide band. The operator of the satellite, Deimos Imaging, was created as a result of a collaboration between the Spanish aerospace engineering company Deimos Space and the Remote Sensing Laboratory of the University of Valladolid (LATUV)). The main goal of the new company is the development, implementation, operation and commercial use of remote sensing systems. The company is located in Valladolid (Spain).
Deimos Imaging is currently developing a high resolution satellite Deimos-2, the launch of which is scheduled for 2013. The Deimos-2 spacecraft is designed to obtain low-cost, high-quality multispectral remote sensing data. Together with the Deimos-1 spacecraft, the Deimos-2 satellite will form a single Deimos Imaging satellite system.
The main characteristics of the spacecraftDeimos-2
Main technical characteristics of spacecraft imaging equipmentDeimos-2
In the next two years, the implementation of the national program for observing the Earth from space PNOTS (Programa Nacional de Observación de la Tierra por Satélite) will begin. KA paz(translated from Spanish as "peace"; another name is SEOSAR - Satélite Español de Observación SAR) - the first Spanish dual-purpose radar satellite - is one of the components of this program. The satellite will be capable of shooting in all weather conditions, day and night, and will primarily fulfill orders from the Spanish government related to security and defense issues. The Paz spacecraft will be equipped with a synthetic aperture radar developed by Astrium GmbH on the radar platform of the TerraSAR-X satellite.
The main characteristics of the spacecraftpaz
Main technical characteristics of spacecraft imaging equipmentpaz
| Spectral range | X-band (3.1cm) | |||
| Mode | Nominal spatial resolution, m | Shooting bandwidth, km | shooting angle range, deg. | Polarization |
| Ultra High Resolution (High Resolution SpotLight - HS) | <(1 х 1) | 5x5 | 15–60 | Single (optional - VV or HH); double (VV/HH) |
| high definition (SpotLight-SL) |
1 x 1 | 10x10 | 15–60 | |
| High Definition Broadband (StripMap - SM) | 3x3 | 30 | 15–60 | Single (optional - VV or HH); double (optional - VV/HH or HH/HV or VV/VH) |
| Medium Resolution (ScanSAR - SC) | 16x6 | 100 | 15–60 | Single (optional - VV or HH) |
In 2014, it is planned to launch another component of the PNOTS KA program Ingenio(another name is SEOSat; Satélite Español de Observación de la Tierra). The satellite will be capable of high-resolution multispectral imaging for the needs of the Spanish government and commercial customers. The mission is funded and coordinated by the CDTI (Centro para el Desarrollo Tecnológico Industrial). The project is controlled by the European Space Agency.
The main characteristics of the spacecraft Ingenio
Main technical characteristics of spacecraft imaging equipment Ingenio
EUROPEAN SPACE AGENCY
In 1998, in order to ensure comprehensive monitoring of the environment, the governing bodies of the European Union decided to deploy the GMES (Global Monitoring for Environment and Security) program, which should be carried out under the auspices of the European Commission in partnership with the European Space Agency (European Space Agency, ESA) and European Environment Agency (EEA). As the world's largest Earth observation program to date, GMES will provide governments and other users with highly accurate, up-to-date and accessible information to better control environmental change, understand the causes of climate change, keep people safe and more.
In practice, GMES will consist of a complex set of observing systems: remote sensing satellites, ground stations, ships, atmospheric probes, etc.
The GMES space component will rely on two types of remote sensing systems: Sentinel satellites specially designed for the GMES program (their operator will be ESA), and national (or international) satellite remote sensing systems included in the so-called GMES assistance missions (GMES Contributing Missions; GCMs) .
The launch of Sentinel satellites will begin in 2013. They will survey using various technologies, such as radar and optoelectronic multispectral sensors.
To implement the GMES program under the general guidance of ESA, five types of remote sensing satellites Sentinel are being developed, each of which will carry out a specific mission related to Earth monitoring.
Each Sentinel mission will include a dual-satellite constellation to provide the best area coverage and faster re-surveys to improve data reliability and completeness for GMES.
Mission Sentinel-1 will be a constellation of two radar satellites in polar orbit equipped with a synthetic aperture radar (SAR) for C-band surveys.
Shooting radar satellites Sentinel-1 will not depend on the weather and time of day. The mission's first satellite is scheduled to launch in 2013, and the second in 2016. Designed specifically for the GMES program, the Sentinel-1 mission will continue the C-band radar surveys initiated and continued by the ERS-1, ERS-2, Envisat satellite systems (operator ESA) and RADARSAT-1,2 (operated by MDA, Canada).
The Sentinel-1 constellation is expected to cover all of Europe, Canada, and major shipping lanes every 1-3 days, regardless of weather conditions. Radar data will be delivered within an hour of the survey, a big improvement over existing radar satellite systems.
The main characteristics of the spacecraftSentinel-1
| Satellite launch dates (planned): 2013 (Sentinel-1A), 2016 (Sentinel-1B) | ||
| Launch vehicle: Soyuz launch vehicle (Russia) | ||
| Developers: Thales Alenia Space Italy (Italy), EADS Astrium GmbH (Germany), Astrium UK (UK) | ||
| Weight, kg | 2280 | |
| Orbit | Type | Polar sun-synchronous |
| Height, km | 693 | |
| Estimated period of operation, years | 7 | |
Main technical characteristics of filming equipmentKASentinel-1
Pair of satellites Sentinel-2 will regularly deliver high-resolution space imagery to the entire Earth, ensuring the continuity of data acquisition with characteristics similar to those of the SPOT and Landsat programs.
Sentinel-2 will be equipped with an opto-electronic multispectral sensor for imaging with a resolution of 10 to 60 m in the visible, near infrared (VNIR) and shortwave infrared (SWIR) spectral zones, including 13 spectral bands, which guarantees the display of differences in the state of vegetation , including temporal changes, and minimizes the impact on atmospheric quality.
An orbit with an average height of 785 km, the presence of two satellites in the mission, will make it possible to conduct repeated surveys every 5 days at the equator and every 2-3 days at middle latitudes. The first satellite is planned to be launched in 2013.
Increasing the swath width, along with a high repeatability of surveys, will make it possible to monitor rapidly changing processes, for example, changes in the nature of vegetation during the growing season.
The uniqueness of the Sentinel-2 mission is associated with a combination of large territorial coverage, frequent re-surveys, and, as a result, the systematic acquisition of full coverage of the entire Earth by high-resolution multispectral imaging.
The main characteristics of the spacecraft satelliteSentinel-2
| Satellite launch dates (planned): 2013 (Sentinel-2A), 2015 (Sentinel-2B) | ||
| Launch pad: Kourou spaceport (France) | ||
| Launch vehicle: RN "Rokot" (Russia) | ||
| Developer: EADS Astrium Satellites (France) | ||
| Operator: European Space Agency | ||
| Weight, kg | 1100 | |
| Orbit | Type | Sun-synchronous |
| Height, km | 785 | |
| Estimated period of operation, years | 7 | |
The main purpose of the mission Sentinel-3 is the observation of ocean surface topography, sea and land surface temperature, ocean and land color with a high degree of accuracy and reliability to support ocean forecasting systems, as well as to monitor the environment and climate.
Sentinel-3 is the successor to the well-established ERS-2 and Envisat satellites. A pair of Sentinel-3 satellites will have a high survey repeatability. Satellite orbits (815 km) will provide a complete data packet every 27 days. The launch of the first satellite of the Sentinel-3 mission is scheduled for 2013, immediately after Sentinel-2. The Sentinel-3B satellite is scheduled to launch in 2018.
The Sentinel-4 and Sentinel-5 missions are designed to provide atmospheric composition data for their respective GMES services. Both missions will be implemented on a meteorological satellite platform operated by the European Organization for Satellite Meteorology EUMETSAT. The satellites are planned to be launched in 2017–2019.
BRAZIL
The aerospace industry is one of the most innovative and important branches of the Brazilian economy. The Brazilian space program will receive $2.1 billion in federal investment over four years (2012-2015).
The National Institute for Space Research (Instituto Nacional de Pesquisas Espaciais - INPE) works together with the Ministry of Science and Technology and is responsible, among other things, for conducting space monitoring.
In cooperation with China, INPE is developing the CBERS family of satellites. Thanks to the successful mission of the CBERS-1 and CBERS-2 satellites, the governments of the two countries have decided to sign a new agreement to develop and launch two more joint satellites. CBERS-3 and CBERS-4 necessary to control deforestation and fires in the Amazon, as well as to solve the problems of monitoring water resources, agricultural land, etc. Brazilian participation in this program will be increased to 50%. CBERS-3 is scheduled to launch in 2013 and CBERS-4 in 2014. The new satellites will be more capable than their predecessors. As a payload, 4 imaging systems with improved geometric and radiometric characteristics will be installed on the satellites. The MUXCam (Multispectral Camera) and WFI (Wide-Field Imager) cameras were developed by the Brazilian side, and the PanMUX (Panchromatic and Multispectral Camera) and IRS (Infrared System) cameras were developed by the Chinese. The spatial resolution (in nadir) in the panchromatic mode will be 5 m, in the multispectral mode - 10 m.
A series of own small satellites is also being developed on the basis of the standard multi-purpose medium-class space platform Multimission Platform (MMP). The first of the satellites is a polar-orbiting small remote sensing satellite Amazonia-1. It is planned to place the Advanced Wide Field Imager (AWFI) multispectral camera, created by Brazilian specialists, on it. From an altitude of 600 km, the camera swath will be 800 km, the spatial resolution will be 40 m. The Amazonia-1 spacecraft will also be equipped with the British optoelectronic system RALCam-3, which will capture images with a resolution of 10 m in a swath of 88 km. Small radar satellite MapSAR(Multi-Application Purpose) is a joint project of INPE and the German Aerospace Center (DLR). The satellite is designed to operate in three modes (resolution - 3, 10 and 20 m). Its launch is scheduled for 2013.
As part of our review, we did not set the task of analyzing all new and promising national remote sensing systems of high and ultra-high resolution. More than 20 countries now have their own Earth observation satellites. In addition to the countries mentioned in the article, Germany (the RapidEye optical-electronic satellite constellation, TerraSAR-X and TanDEM-X radar spacecraft), Israel (EROS-A, B), Italy (COSMO-SkyMed-1- 4), etc. Every year this unique space club is replenished with new countries and remote sensing systems. In 2011–2012 Nigeria (Nigeriasat-X and Nigeriasat-2), Argentina (SAC-D), Chile (SSOT), Venezuela (VRSS-1) and others have acquired their satellites. 2.5 m, in multispectral imaging - 10 m) continued the Turkish remote sensing program (the launch of the third satellite of the Gokturk series is scheduled for 2015). In 2013, the United Arab Emirates plans to launch its own ultra-high resolution satellite Dubaisat-2 (resolution in panchromatic mode is 1 m, in multispectral mode - 4 m)
Work is underway to create fundamentally new space monitoring systems. Thus, the American company Skybox Imaging, based in Silicon Valley, is working on the creation of the world's most high-performance innovative constellation of remote sensing mini-satellites - SkySat. It will make it possible to obtain high-resolution satellite images of any region of the Earth several times a day. The data will be used for emergency response, environmental monitoring, etc. The survey will be conducted in panchromatic and multispectral modes. The first satellite of the constellation, SkySat-1, is scheduled to be launched in 2013. After the constellation is fully deployed (and it is planned to have up to 20 satellites in orbit), users will be able to view any point on the Earth in real time. It is also planned to conduct video filming from space.
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