Classification of objects from space

Abstract

Using a satellite in orbit above the Earth, on a single path over the target area, numerous synthetic aperture radar (SAR) images of the target area on Earth are acquired. [Solution] In some methods, data for each image is acquired from different incident angles to the target region. Next, the variation in the amount of backscatter with respect to the incident angle is analyzed and used to identify the object being imaged by the pixel or group of pixels. In other methods, data for each image is acquired from different incident angles to the target region, and these different incident angles are determined based on the specular reflection curve for each individual object. Then, the amount of backscatter is analyzed and it is determined whether or not a particular object is present based on the amount of backscatter. For example, "extended dwell spotlight acquisition" geometry can be used in which an image data acquisition device can be fixed to illuminate the same target as a satellite passes over the target for 20 seconds.

Description

Technical Field

[0001] The present invention relates to earth observation. The present invention can be implemented by communication satellites and other types of spacecraft.

Background Art

[0002] Communication satellites orbiting around the Earth have come to be frequently used for various purposes such as, for example, tracking the position of objects, on-site surveys, and observing changing weather patterns.

[0003] Many modern artificial satellites are equipped with synthetic aperture radar (SAR). These types of radar can be used to create 2D and 3D area images on the surface of the Earth.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Recently, there has been an increasing interest in the use of artificial satellites for detecting water on the Earth, such as floods in urban areas or other regions. However, this is an example of the problem that conventional SAR detection / classification methods (such as polarization, threshold processing, change detection, statistical analysis, etc.) are insufficient. This is due to the fact that large differences in reflectivity, complex multi-path reflections, and no large release areas make it very difficult to achieve statistical or texture analysis.

Means for Solving the Problems

[0005] In one aspect of the present invention, there is provided an earth observation method as follows: using an artificial satellite moving in an orbit above the Earth to acquire a number of synthetic aperture radar (SAR) images of a target area on the Earth.

[0006] In some methods, data for each image is acquired by using different angles of incidence to the target region. Subsequently, for at least one pixel or group of pixels in the image, the variation in the amount of backscatter with respect to the angle of incidence is analyzed and used to identify the object imaged by the pixel or group of pixels. Identifiable objects include features of the Earth's surface, whether constructed, cultivated or natural (such as towns or cities), and specific objects such as water, crops, roads and forests, as well as other objects that a person skilled in the art might conceive of.

[0007] In another method, data for each image is acquired from different incident angles relative to the target region, and these different incident angles are determined based on the specular reflection curve for a specific object, such as a particular substance. Then, for at least one pixel or group of pixels in the image, the amount of backscattered radiation is analyzed, and based on the amount of backscattered radiation, it is determined whether or not an individual object is present.

[0008] While the above method can be achieved within a continuous satellite path, the orientation of the satellite's image acquisition device relative to the target region can be controlled to remain pointed towards the target region for a specific period as the satellite passes over it. This allows for the acquisition of numerous images in a single satellite path over the target region.

[0009] Some embodiments of the present invention can be implemented by appropriately controlling a satellite already in orbit, and thus can be achieved using appropriate algorithms that run in a processor on an existing satellite. Accordingly, in some embodiments, the present invention provides instructions that, when executed on one or more processors on a satellite, result in the implementation of any of the methods described herein. The instructions can be provided in a computer-readable medium, such as a signal transmitted from Earth to the satellite.

[0010] This summary is provided to introduce the conceptual options in a simplified form, and it should be understood that they will be explained in more detail in the "Detailed Explanation" section below.

[0011] This abstract does not identify the main or essential features of the claimed subject area, nor is it intended to be used to determine the scope of the claimed subject area.

[0012] Several embodiments of the present invention will be described as examples with reference to the drawings shown below. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram showing the differences in the change in backscattering intensity with respect to the angle of incidence of water and forest, according to several embodiments of the present invention. [Figure 2] Figure 2 is a schematic diagram illustrating a method implemented by acquiring image data along a continuous path of a satellite over a target region, according to several embodiments of the present invention. [Figure 3] Figure 3 is a schematic diagram illustrating a method implemented by acquiring image data in a single path of a satellite over a target region, according to several embodiments of the present invention. [Figure 4] Figure 4 shows an example of an image obtained by one method according to several embodiments of the present invention. [Figure 5] Figure 5 is a flowchart showing one method of Earth observation according to several embodiments of the present invention. [Figure 6] Figure 6 is a schematic diagram of the components of a satellite 140 that communicates with a ground station, according to several embodiments of the present invention. [Figure 7] Figure 7 is a perspective view of an artificial satellite in orbit above the Earth, according to several embodiments of the present invention. [Modes for carrying out the invention]

[0014] The present invention will be understood by the following detailed description of embodiments, which is provided as an example only and is not intended to be limiting. For the sake of brevity, details of some well-known forms, methods, systems, processes, components, circuits, etc., which are considered to be well known to those skilled in the art, are not described.

[0015] Some embodiments of the present invention provide Earth observation methods for identifying or classifying objects, such as matter, using information obtained from artificial satellites. The term “matter” is used here in a broad sense and refers to all things covering the Earth’s surface, including but not limited to water, forests, grasslands, cultivated crops, building materials, or other things.

[0016] The reflection of radiation from a surface, such as radar, may be due to a combination of ordinary reflection or "specular" reflection and backscattering or diffuse reflection. Some materials are known to have a different "specular reflection curve" than others, indicating a dependence of radiation or backscatter brightness on the radiation incidence angle. The same is true for other types of objects. For example, water has a specific specular reflection curve that is very different from that of a forest. At small incidence angles, the surface of water reflects most of the energy like a mirror; in other words, most of the reflection is specular. At larger incidence angles, the surface reflects energy forward, resulting in very low backscatter measurements. In contrast, for example, a forest or grassland returns more diffuse scattering, and the dependence of backscatter energy on the incidence angle is much smaller. Figure 1 is a schematic diagram of the backscatter intensity as a function of incidence angle for water and a forest, illustrating the contrasting properties of these two different materials. Differences in specular reflection can be used to identify a wide range of objects, including but not limited to those described above. For example, agricultural land at various stages of growth will have a specific "specular reflection curve." If precise identification is not possible, objects can be classified, for example, by identifying their general type, using methods according to several embodiments. Therefore, in all embodiments described, "classification" of a substance or object can be used instead of "identification."

[0017] Other bright reflective targets, such as buildings, may have a strong dependence on the angle of incidence, but often bright dispersion occurs at various corners, and the cutoff angle for bright reflection is very different from that of water. Furthermore, building walls have a very different dependence because they are vertical.

[0018] According to some embodiments of the present invention, an object can be identified using SAR image data and information obtained from a satellite in orbit around the Earth. For example, a satellite can be used to acquire multiple images of a target area on Earth, and data for each image obtained from different incident angles or angular positions with respect to the target area can be acquired. Thereafter, the image data can be analyzed for changes in the amount of backscattered radiation with respect to the angular position, for example, on a pixel-by-pixel or group-of-pixels basis. Using this analysis, the object imaged in the pixel or group of pixels can be identified.

[0019] For example, in the case of a satellite with a pre-determined "flight path" such as a fixed orbit around the Earth, the possibility of acquiring image data from different angular positions with respect to a single target is limited. Many possibilities regarding specific embodiments of the present invention are described in more detail below.

[0020] By using a suitable range of different incident angles, multiple different types of objects can be identified in the target area. By using an incident angle based on known backscattering characteristics for a particular substance, it is also possible to identify a single substance in the target area using a method according to some embodiments. Therefore, different incident angles for acquiring image data can be determined based on the characteristics of the individual substances known, and based on the amount of backscattered radiation, it is possible to determine whether that individual substance exists on Earth, for example, compared to other parts of the target area. Water is an example of a substance particularly suitable for this type of process. For example, a similar process can be used to distinguish a building area from other areas of the Earth's surface.

[0021] It should be noted that it is not necessary to prepare a visible image to implement an embodiment of the present invention. For this reason, the term "image" as used herein can be interpreted to mean a pixel by pixel intensity reading, unless otherwise specified.

[0022] [Acquisition of Images] A satellite usually equipped with an image acquisition device known in the art will be further described with reference to FIGS. 6 and 7. The method according to some embodiments of the present invention can, in principle, be carried out by acquiring image data in a continuous path of a satellite over a target area, in which image data acquisition will probably not require turning the image acquisition device in a new direction with respect to the target. For example, a technique of acquiring image data at different positions in a continuous path, known as the "cross-track" mode, is used. This overview is shown in FIG. 2. Here, it will be understood that the satellite is "looking sideways". In other words, the image data is not collected from the area directly below the satellite. Without turning the image acquisition device in a new direction between paths, the target T is imaged at position 1 at angle 10° at time t1 in path 1, at time t2 at angle 15° in path 2, and at position 3 at angle 30° at time t3 in path 3. Although different angles are described as examples, other angles and path numbers can also be used.

[0023] Experiments using the continuous images obtained in this way have demonstrated that, due to the known dependence of backscattering on the angle of incidence, water in a relatively complex environment can be reliably identified. Furthermore, it has been demonstrated that this can be achieved within a limited range of incident angles, usually greater than 10° positive or negative in magnitude, and often with an upper limit of 30°, which can be achieved using a sideways-looking satellite. However, if importance is attached to performing object identification more quickly, according to some embodiments of the present invention, image data can be acquired in a single path of the satellite.

[0024] For example, it is known that SAR radar is operated in "spotlight" mode from a satellite to obtain higher-resolution images of a specific target. In this mode, any change in the incidence angle of the image acquisition device or radar source to the target is negligible. According to some embodiments of the present invention, the orientation of the image acquisition device to the target can be controlled by keeping it pointed towards the target area for a predetermined period of time while the satellite is passing over the target area, thereby enabling the acquisition of image data from multiple different angles in a single path of the satellite over the target area. This can be called an "extended dwell spotlight acquisition" geometry, which is different from what is known as a "cross-track" geometry. In an example of extended dwell, the image data acquisition device is fixed and illuminates the same target for, for example, 20 seconds as the satellite passes over the target. However, it should be noted that embodiments of the present invention are not limited to the implementation of a pure spotlight mode, and other modes that enable data acquisition from multiple different angles may also be used, such modes are described below.

[0025] The image acquisition device can reduce the frequency of image data acquisition because it "looks" at the same target for a longer period of time than usual. In some embodiments of the present invention, for example, the quality of images in the process of identifying objects on Earth may be sacrificed to save processing time and associated power.

[0026] Figure 3 schematically illustrates a method implemented by acquiring image data in a single path of a satellite over a target area, according to several embodiments of the present invention. Here, the target can be imaged at position 1, angle 10°, which is closest to the "cross-track" position in Figure 2. In addition, by orienting the image acquisition device toward the target, one image can be acquired at position 2, angle 30°, in the same path of the satellite. Similarly, one image can be acquired at -30° and at some angle in between. In other words, in a single path of the satellite, there can be several data acquisitions corresponding to several images.

[0027] This method can be used to acquire image data and identify or classify objects in real time, virtually instantaneously, rather than through multiple paths. Since conditions such as the extent of water can change dramatically between satellite passes, this method can be extremely important, for example, in flood detection. The method shown in Figure 3 allows for the creation of a variety of meaningful incidence angles in a single satellite path.

[0028] As mentioned above, in the actual satellite scenarios described further below, a satellite may illuminate the same target for up to 20 seconds as it passes over it (compared to the typical 2 to 3 seconds in known "spotlight" images).

[0029] In most cases, the instantaneous incidence angle is generated forward, but sometimes it can be generated backward along the flight path, or both forward and backward (contrary to the conventional definition of cross-track incidence angle, but a perfectly valid incidence angle from the perspective of reflection). For flood detection in urban areas, for example, an additional advantage of using small incidence angles of 10-20 degrees, and / or both forward and backward incidence angles, is that it can generate inter-building situation maps more effectively than SAR acquisition with conventional large incidence angles, which are typically 35-50 degrees.

[0030] Figure 3 shows that the distance between the satellite and the target region changes between positions 1, 2, and 3. Here, position 2 is the closest position to the target region, and it is the position where the incident angle is zero degrees (directly overhead) as close as possible. The force due to reflection or backscatter received at a large incident angle decreases with increasing distance between the satellite and the target, but this may limit the range of possible incident angles, and it may be necessary to adjust the force due to reflection to compensate for this.

[0031] Image data obtained from a satellite using either a multi-path or single-path approach can be used to analyze the change in the amount of backscatter with respect to angular position, for the purpose of identifying objects imaged by pixels or groups of pixels. The analysis of the image data obtained from the satellite is performed on the satellite or at one or more ground stations.

[0032] In this way, according to some embodiments of the present invention, multiple images of a target can be obtained using different angles of incidence. Then, in urban areas and other relatively complex regions and environments, objects observed in the images, such as water, can be classified based on the known dependence of backscatter or reflection on the angle of incidence.

[0033] As mentioned above, for the purpose of identifying objects in a single image, lower resolution image data may suffice compared to what is required for other Earth observation tasks. Therefore, the frequency of data acquisition can be reduced, thereby saving power and processing power.

[0034] According to some embodiments of the present invention that use a single path to acquire the aforementioned image data, the image data can be acquired at specific or discrete intervals, thereby intentionally ignoring gaps between acquisition periods while pointing to the same target. For example, when a satellite flies over a target such as a city, the spotlight points to the target for 50 seconds before and 50 seconds after it is closest to the target (directly above the target) (a total of 100 seconds), with a 5-second acquisition period every 20 seconds, and can have five times the "looks" of 5 seconds in total without using image creation energy for the entire 100 seconds, while allowing for large changes in the angle of incidence. During each interval, the orientation of the image acquisition device relative to the target area can be controlled relative to the target, and although the image acquisition process is interrupted, images are acquired over a continuous angular range. In other words, for continuous or normal image data acquisition, the orientation of the image acquisition device is controlled as the satellite passes over the target, compensating for the satellite's movement along its orbit and keeping the image acquisition device pointed towards the target. To enable image acquisition at intervals, the aforementioned orientation change is further controlled, allowing for image acquisition across a continuous angular range while interrupting image data acquisition.

[0035] Some embodiments of the present invention can be implemented using small, agile satellites, such as those operated by ICEYE OY. By using such satellites and controlling the orientation of the satellite relative to the target area, the orientation of the image acquisition device relative to the target can be controlled. In other words, the orientation of the image acquisition device relative to the target area can be changed by moving the entire satellite. Therefore, it is not necessary to change the orientation of the image acquisition device relative to the satellite body. On the other hand, if the satellite is larger, for example, controlling the orientation of the image acquisition device may require readjusting the orientation of the image acquisition device relative to the satellite body, for example by using one or more motors on the satellite.

[0036] [Image data analysis] The following is an example of how image data can be acquired, analyzed, and displayed according to some embodiments of the present invention.

[0037] The task in this example was to generate a single image of a city in a single satellite path, so that water, particularly water between buildings caused by flooding, could be identified. The process began by setting the image acquisition mode to what is known in this art as a "spotlight," that is, to illuminate a single target area continuously. In this example, the period was set to 40 seconds. This would depend on a variety of factors, including, but not limited to, one or more angular ranges involved and the satellite's flight speed.

[0038] In this example, 10° was determined as the smallest angle of incidence to the target, which results in high backscatter from the water. It should be noted that the satellite rarely flies directly above the target point. The minimum angle of incidence is determined by the closest angle of incidence. Only in the special case where the satellite passes directly above the target point does the minimum angle of incidence become zero (however, SAR imaging requires a lateral geometry, meaning that imaging at an angle of 0° does not result in a single image). According to some embodiments of the present invention, different angles of incidence from which image data is acquired are preset based on known characteristics such as the angle of incidence of an object, such as the substance to be identified, or its dependence on the specular reflection curve.

[0039] In this example, the "edge," that is, the furthest point from which valid data would be obtained, was determined to be at a flight time of + / - 20 seconds from the center or directly overhead, where the incident angle (where backscattering from water is low) is approximately 20°. Therefore, the incident angle range was determined to be 10° to 20°.

[0040] Next, numerous high-resolution "appearances" in the target region were processed within an incidence angle range of 20° at the edges and 10° at the center.

[0041] Each "appearance" or image corresponds to a different angle of incidence. Therefore, by analyzing the reflected radiated power with respect to the angle of incidence, it is possible to identify objects pixel by pixel or in groups of pixels. This analysis can be used to identify objects in an image.

[0042] The analysis can be performed by a computing system mounted on the satellite. Alternatively, the image data may be transmitted to a ground station in any manner known in the art for analysis. The data can be displayed at one or more ground stations.

[0043] According to some embodiments of the present invention, lookup tables or other reference data can be used to identify ground objects from image data, and their correlation with the image data obtained by the processing described in this example can be examined. It will be understood that such a process may be augmented using machine learning to improve the reliability of object identification.

[0044] According to some embodiments of the present invention, a multi-channel raster can be generated from "appearances," such as image data for each incident angle, thereby allowing objects to be classified according to their response and optionally presented as images on a display. In some embodiments, subsets of different incident angles can be assigned to each primary color to produce a visually appealing display, and the summed intensity values ​​can be used to generate a color representation of a target area. To generate a single image, red, green, and blue (RGB) channels can be specified, where R is the sum of appearances at incident angles greater than 15°, G sum is the sum of appearances at incident angles between 15° and 10°, and G is the appearance at an incident angle of 10°. In such an image (bright in channel B and dark in others), water should appear "blue," and a diffuse target should appear "white" (equally bright in all channels).

[0045] Figure 4 shows an example of a two-channel image generated from two acquisitions, with the difference between large and small incidence angles highlighted. Here, the river R can be identified along with other patches of water W.

[0046] Figure 5 shows a method of Earth observation according to several embodiments of the present invention, the method shown in Figure 5 being an example of the method used to produce the image in Figure 4. Although Figure 5 uses an example of a specific material, the method can be used for general objects as described in other sections of this specification.

[0047] In methods according to some embodiments of the present invention, the first step may be target identification. This can be achieved by many methods. In some embodiments, a target region can be communicated to a satellite from a ground station, for example, following observations by a human on the ground, or following the automatic detection of a region requiring observation. Alternatively, one or more algorithms executed on the satellite can identify a target region. Any other method can be used to identify a target region.

[0048] In operation 502, image data is acquired. This acquired data can take the form of one set of image data, that is, one data set corresponding to each of the different incident angles for the same target region. Then, as described above, for the purpose of identifying the material imaged by a pixel or group of pixels, the change in the amount of backscatter radiation, which is typically represented by the pixel intensity value, can be analyzed for each pixel or group of pixels represented in the image data.

[0049] In one example, the analysis may consist of operations 504 to 508 in Figure 5.

[0050] Operation 504 consists of assigning at least two subsets of incident angles to each channel. In the example shown in Figure 4, two subsets of angles, one greater than and one less than a predetermined threshold, were used. When the data is displayed, the channels can display color. This assignment can be done before acquiring the image data, for example, based on the known specular reflection properties of the material of interest. Typically, one subset is a sub-range of the entire range of incident angles, but this is not the case for a particular material.

[0051] Operation 506 consists of summing the pixel intensity values ​​from the image data of each set for each angle of each subset. For example, the results of one set, which are greater than and less than the angle threshold, would be one intensity value for each channel. This can be done for groups of pixels rather than for each pixel.

[0052] Operation 508 consists of using the analysis, for example, the analysis of channel intensity values ​​to identify a single substance in a pixel or group of pixels. In the example in Figure 4, this was used to distinguish water from other substances on the Earth's surface.

[0053] As shown in the two-color example in Figure 4, the combined intensity values ​​can be displayed on a visual display by assigning a color to each channel, for example, in the form of an image of the target region. It will be understood that a one-to-one correspondence between a substance and a channel is not necessarily maintained, as some substances may produce a single intensity value in two or more channels.

[0054] In the three-channel example described above, RGB values ​​can be used to generate a visual representation of the distribution of one or more substances in a target region. It will be understood that embodiments of the present invention are not limited to the use of RGB as primary colors, or to the use of only three primary colors.

[0055] As can be understood from the above, methods according to some embodiments of the present invention can be modified to identify individual substances. For example, although two- and three-channel processing is described above, "single-channel" processing is also possible, where different angular positions or incident angle ranges are predetermined based on known properties of the substance in question, such as the specular reflection curve of water. Then, the presence or absence of the substance can be determined based on the amount of backscatter in such incident angle ranges. For example, the pixel intensity values ​​in that incident angle range can be summed and visually presented in grayscale, where darker areas indicate a high probability of the substance being present. The same can be done for more general object identification.

[0056] The method may include displaying an image in operation 510.

[0057] The above describes several specific embodiments of the present invention. Other applications of the present invention include the following:

[0058] By using embodiments of the present invention, it is possible to classify non-water materials, such as agricultural land at various stages of growth, which would have a specific "specular reflection curve."

[0059] As previously stated, embodiments of the present invention are not limited to those understood as purely “staring spotlight” imaging modes. As those skilled in the art know, various modes of SAR operation are known and under development, including, but are not limited to, staring spotlight, sliding spotlight, and “orbital ScanSAR,” which is described in detail in “TerraSAR-X Staring Spotlight Optimisation and Global Performance Predictions,” IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Vol. 93 March 2016. To apply to a wider area, for example, “orbital ScanSAR” type imaging can be used, but this will sacrifice resolution, although the total number of incident angles will not be sacrificed (while “sliding spotlight” geometry would also enable imaging over a wider area, but the usable angles will be limited).

[0060] [Image acquisition device] Apparatus suitable for carrying out methods according to several embodiments of the present invention will be described here with reference to Figures 6 and 7. Figures 6 and 7 are schematic and perspective views, respectively, of the components of a satellite 140 that communicates with a target location and / or a ground station 120 on Earth. A more detailed description of an example of the satellite structure is provided in WO2020094872 (A1).

[0061] In Figure 6, one-way solid arrows between components are used to indicate power connections, two-way solid arrows are used to indicate RF signal connections, and dotted lines are used to indicate data connections.

[0062] The satellite body, indicated by rectangle 120 in Figure 6, is provided with several components, some of which are mounted on the wings, indicated by rectangle 130 in Figure 6. The satellite components shown in Figure 6 consist of a power supply 101 and a power distribution system 102. The power supply 101 and power distribution system 102 supply power to the propulsion system 190, the propulsion controller 109, the computing system 103, and the communication system 104. The propulsion controller 109 is shown here as a separate item, but in practice it may form part of the computing system 103. The propulsion controller may be configured to control the orientation of the image acquisition device on satellite 140 according to some embodiments of the present invention, either through the use of control software implemented on one or more processors included in the propulsion controller 109, or in response to commands received, for example, from the computing system. When commands are transmitted from the computing system 103, this computing system can be considered to consist of the propulsion controller.

[0063] The power supply 101, the power distribution system 102, the computing system 103, and the communication system 104 are collectively referred to in the art as the satellite "bus." The communication system 104 may include, for example, one or more antennas installed on the satellite body. Alternatively, the communication system 104 may transmit and receive signals via one or more antennas on the wings 130.

[0064] In the case of an Earth observation satellite, one or more radar antennas 106 or antenna arrays can be installed on one or more wings 160. Each antenna 106 or antenna array may have a corresponding amplifier 107. This amplifier 107 is powered from a power supply 101 via a power distribution system 108 and, for example, via a power distribution system 102. As is known to those skilled in the art, the antenna 106, together with the amplifier 107 and the power distribution system 108, collectively form an image acquisition device as described in other sections of this specification. These can also perform functions other than image data acquisition. As is known in the art, both the power distribution systems 102 and 108 may include control logic.

[0065] As is well known to those skilled in the art, the amplifier 107 may, in the illustrated example, have a two-way data communication link with the computing system 103 via the power distribution system 108 and may be configured to transmit data to the computing system 103, such as data related to radar signals received via a transceiver (not shown). Such data may include image acquisition data according to some embodiments of the present invention. The acquired image data may be processed by the communication system 103 to form an image, identify objects on Earth as described in other sections, and then output to the communication system 104 for forward transmission. Alternatively, the raw data may be output by the computing system 103 to the communication system 104 for processing by a remote computing system located, for example, at a ground station or on another satellite. As is well known to those skilled in the art, the computing system 103 may transmit operation instructions, data requests or other signals to the amplifier 107, for example, via the power distribution system 108.

[0066] The communication system 104 can communicate with an earth station such as a ground station 200 or other satellites using radio frequency communication, light such as laser communication, or other forms of communication known in the art.

[0067] Figure 7 is a perspective view of a satellite 140 orbiting in space, which can contain the components of Figure 6. The satellite in Figure 7 consists of a body 110, which can house some of the components of the body 120 in Figure 6, or some of the components of Figure 6 can be installed in the body 110. The body 110 can also house one or more batteries. For example, the body 110 can be partially sealed to house and protect the components. The housing provides a surface on which components can be installed. In the example in Figure 7, the solar panel 150 is installed on one rectangular surface of the body 110, and an additional solar panel 155 is attached to the panel 150 by struts 115.

[0068] The artificial satellite 140 consists of two generally planar structures extending in opposing directions from the main body 110, thereby obtaining two "wings" 160. It is shown that the structure consisting of the wings 160 is mounted on or near the rectangular surface of the main body 110. The main body 110 and the wings 160 together are collectively called the spacecraft frame. One or more of the above-mentioned antennas can be mounted on the artificial satellite "wings". The artificial satellite 140 is provided with a propulsion system 190 that steers the artificial satellite using the thrust it generates.

[0069] In embodiments of the present invention, the orbit or orbital path of the satellite is not limited and may include, for example, any geostationary orbit (GEO), low Earth orbit (LEO), medium Earth orbit (MEO), polar orbit and sun-synchronous orbit (SSO), transfer orbit and geostationary transfer orbit (GTO), and Lagrangian points (L points). However, in some embodiments of the present invention, those skilled in the art will readily understand that testing the satellite in a laboratory (e.g., such as a ground-based test facility) may be required before launch into space.

[0070] Satellites according to some embodiments of the present invention may consist of systems not detailed herein, such as, but are not limited to, thermal control systems and attitude control systems for ensuring that the satellite is oriented in the correct direction.

[0071] In this specification, the term “computing system” refers to a device or group of devices having processing capabilities capable of performing instructions. Those skilled in the art will recognize that such processing capabilities are incorporated into many different devices, and therefore, as used herein, the term “computing system” can include PCs, servers, and many other devices.

[0072] The components described herein do not necessarily need to be physically isolated from one another unless otherwise specified, and the functionality of the components shown in the diagrams can be distributed or shared between different or the same physical devices. For example, some functions of a communication system can be performed by a computing system, and vice versa.

[0073] It will be understood that the advantages and benefits described above may relate to one embodiment or to several embodiments. The embodiments are not limited to those that solve some or all of the problems described or that possess some or all of the advantages and benefits described.

[0074] A reference to an item “one” refers to one or more of those items. In this specification, the term “comprising” is used to mean including the steps or elements of an identified method, but such steps or elements do not include an exclusive list, and the method or apparatus may include additional steps or elements.

[0075] As used herein, the terms “component” and “system” may include computer-readable data storage consisting of computer-executable instructions that trigger specific functions to be performed when executed by a processor. Such computer-executable instructions may include routines, functions, and so on. It should also be understood that a component or system may be located in a single device or distributed across several devices.

[0076] Furthermore, insofar as the term “include” is used in either the detailed description or the claims, such term is intended to be as comprehensive as the term “include” is interpreted when “include” is used as a transitional term in the claims.

[0077] Each figure illustrates an exemplary method. While the method is shown and described as a series of actions performed in a specific sequence, it should be understood and acknowledged that the method is not limited by the order of the sequence unless otherwise specified. For example, some actions may occur in a different order than those described herein. In addition, one action may occur simultaneously with others. Furthermore, in some cases, not all actions may be necessary to carry out the method described herein.

[0078] The above description of embodiments is merely illustrative, and it will be understood that various modifications can be made by those skilled in the art. The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible modifications to the above apparatus or method for the purpose of illustrating the aforementioned embodiments, but those skilled in the art will recognize that many further modifications and rearrangements are possible in various embodiments. Accordingly, the embodiments described are intended to encompass all modifications, modifications, and changes included in the appended claims.

Claims

1. Earth observation methods including the following: The acquisition of numerous synthetic aperture radar (SAR) images of a target area on Earth using an artificial satellite orbiting the Earth, where the data for each image is acquired from different angles of incidence to the target area. For at least one pixel or group of pixels in the aforementioned image, analysis of the change in backscattered dose with respect to the angle of incidence. The use of analytical methods to identify objects imaged by pixels or groups of pixels.

2. Earth observation methods including the following: Using satellites orbiting the Earth, multiple synthetic aperture radar (SAR) images of a target area on Earth are acquired. The data for each image is obtained from different angles of incidence on the target area, and the various angles of incidence are determined based on the specular reflection curve of a particular object. For at least one pixel or group of pixels in the aforementioned image, analysis of backscatter dose, Determination of whether or not a specific object is present based on backscattered radiation dose.

3. The method according to claim 1 or 2, wherein the different angles of incidence described above are 10° or larger.

4. The method of claim 3, wherein the different angles of incidence are in the range between 10° and 30°.

5. The method of claim 2, wherein the specific substance is water.

6. The method according to claim 3, wherein the data for each image is acquired at different locations along the continuous path of the satellite over the target region.

7. A method according to any one of claims 1 to 5, comprising controlling the orientation of an image acquisition device on the satellite with respect to the target region, keeping it pointed toward the target region for a predetermined period of time as the satellite passes over the target region, and acquiring a large number of images in a single path of the satellite over the target region.

8. The method of claim 7, wherein the control of the orientation of the image acquisition device with respect to the target is achieved by controlling the orientation of the satellite with respect to the target region.

9. The method according to claim 7 or 8, comprising acquiring image data at discrete intervals within the predetermined period.

10. The method of claim 9, comprising controlling the orientation of the image acquisition device to enable the acquisition of image data from different angular positions within a continuous range relative to the target during discrete intervals within the predetermined period.

11. The method according to any one of claims 1 to 10, wherein the analysis comprises assigning at least two subsets of incident angles to each channel and summing the pixel intensity values ​​so that one intensity value is calculated for each channel.

12. The method of claim 11, comprising representing the sum of intensity values ​​on a visual display.

13. The method of invoice 11 or 12, comprising assigning the aforementioned subsets of different incidence angles to each of the primary colors for visual display, and using the combined intensity value to generate the color representation of the target area.

14. The method according to any one of claims 1 to 13, wherein at least some of the incidence angles are generated rearward along the flight trajectory of the artificial satellite.

15. A computer-readable medium comprising instructions that, when executed on one or more processors in a satellite, cause the execution of the method according to any one of claims 1 to 14.

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