CN109993795B - Method, device, electronic equipment and medium for resolving SAR image ground position - Google Patents

Method, device, electronic equipment and medium for resolving SAR image ground position Download PDF

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CN109993795B
CN109993795B CN201910278613.4A CN201910278613A CN109993795B CN 109993795 B CN109993795 B CN 109993795B CN 201910278613 A CN201910278613 A CN 201910278613A CN 109993795 B CN109993795 B CN 109993795B
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尤红建
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Abstract

A method for resolving the ground position of an SAR image is applied to the technical field of remote sensing image processing and comprises the following steps: the method comprises the steps of establishing a station center three-dimensional rectangular coordinate system by taking a central point of a ground measurement area corresponding to an SAR image as an origin, taking a meridian direction as an X axis and taking a normal direction perpendicular to the earth surface as a Z axis, calculating coordinates of ground points corresponding to pixel points in the SAR image in the station center three-dimensional rectangular coordinate system, and converting the coordinates of the ground points in the station center three-dimensional rectangular coordinate system into coordinates in a station center earth fixed coordinate system to obtain the ground position of the ground points. The disclosure also provides a device for resolving the SAR image ground position, electronic equipment and a storage medium. The method can solve the problem that the ground coordinates cannot be directly and explicitly solved for the satellite-borne SAR image in the prior art.

Description

Method, device, electronic equipment and medium for resolving SAR image ground position
Technical Field
The disclosure relates to the technical field of remote sensing image processing, in particular to a method, a device, electronic equipment and a medium for resolving the ground position of an SAR image.
Background
Synthetic Aperture Radar (SAR for short) is a high-resolution imaging Radar with all-time and all-weather observation capability. Currently, satellite-borne SAR has been widely used in military and civil engineering.
In practical application, it is sometimes necessary to provide an SAR image in real time and give an accurate geographical position of a place shown by the SAR image, which requires that the SAR satellite has a technology for resolving the ground position of the SAR image in real time in orbit.
The existing SAR image ground positioning technology is generally used for carrying out ground positioning on the basis of a distance-Doppler model and a geophysical model, but in the existing resolving method for the ground position of the satellite-borne SAR image, the time consumption is long because a plurality of iterations are required in some methods, the earth ellipse model is not considered in some methods, the earth model is regarded as a sphere for calculation, the calculation result is inaccurate, the used parameters of some methods are more, and the calculation process is complex. Considering the limited computing performance and memory of the on-satellite on-orbit computer, the methods are not suitable for the real-time computation of the on-satellite on-orbit SAR image.
Disclosure of Invention
In view of the above problems, the invention provides a method for resolving the ground position of an SAR image on an on-board satellite, so as to solve the problem that the ground coordinate cannot be directly and explicitly resolved according to the characteristics of a satellite-borne SAR image in the existing method.
One aspect of the present disclosure provides a method for resolving a ground location of an SAR image, including: establishing a station center three-dimensional rectangular coordinate system by taking the central point of the SAR image corresponding to the ground measurement area as an original point, the meridian direction as an X axis and the normal direction perpendicular to the earth surface as a Z axis; calculating the coordinates of ground points corresponding to the pixel points in the SAR image in the station center three-dimensional rectangular coordinate system; and converting the coordinates of the ground points in the station center three-dimensional rectangular coordinate system into coordinates in a ground center and ground fixation coordinate system so as to obtain the ground positions of the ground points.
Optionally, the calculating coordinates of ground points corresponding to pixel points in the SAR image in the station center three-dimensional rectangular coordinate system includes: acquiring the position and the speed of an SAR satellite for shooting the SAR image in the geocentric geostationary coordinate system; converting the position and the speed of the SAR satellite in the geocentric geostationary coordinate system into the position and the speed in the station-centric three-dimensional rectangular coordinate system; calculating the distance from the SAR satellite to the ground based on the distance coordinate value of the SAR image pixel point corresponding to the ground point in the SAR image; calculating two intermediate parameters for calculating the coordinates of the ground point in the station center three-dimensional rectangular coordinate system based on the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system; and calculating the coordinates of the ground point in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center based on the two intermediate parameters, the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the three-dimensional rectangular coordinate system of the station center.
Optionally, the converting the position and the speed of the SAR satellite in the geocenter geostationary coordinate system into the position and the speed in the station-center three-dimensional rectangular coordinate system includes: the coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geodetic coordinate system is (B)0，L0，H0) The coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geostationary coordinate system is (X)0，Y0，Z0) The coordinate of the SAR satellite in the geocentric geostationary coordinate system is (X)s，Ys，Zs) The SAR satellite has a velocity of (V) in the geocentric geostationary coordinate systemX，VY，VZ) The position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The SAR satellite has a speed of (V) in the three-dimensional rectangular coordinate system of the station centerX *，VY *，VZ *) And then:
Figure BDA0002020208850000021
Figure BDA0002020208850000022
Figure BDA0002020208850000023
Figure BDA0002020208850000024
Figure BDA0002020208850000025
Figure BDA0002020208850000026
optionally, the calculating the distance from the SAR satellite to the ground based on the distance coordinate value of the SAR image pixel point corresponding to the ground point in the SAR image includes: setting the distance from the SAR satellite to the ground as R, and setting the distance coordinate value of an SAR image pixel point corresponding to the ground point in the SAR image as x; the near point slant distance is r0The resolution of the slant distance is MxAnd then:
R＝r0+x·Mx。
optionally, the calculating two intermediate parameters for calculating the coordinates of the ground point in the station center three-dimensional rectangular coordinate system based on the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system includes: let lx and ly represent the two intermediate parameters, R represents the distance from the SAR satellite to the ground, and λ is ReyeWavelength of arrival, fDIs the Doppler center frequency, (V)X *，VY *，VZ *) Representing the speed, Zs, of the SAR satellite in the three-dimensional rectangular coordinate system of the station center*Representing the Z-axis coordinate of the SAR satellite in the three-dimensional rectangular coordinate system of the station center, and H represents the height of the ground point in the geocentric geodetic coordinate system, then:
Figure BDA0002020208850000031
Figure BDA0002020208850000032
optionally, the calculating coordinates of the ground point in the three-dimensional rectangular coordinate system of the station center in the X-axis direction and the Y-axis direction based on the two intermediate parameters, the distance from the SAR satellite to the ground, and the position and the speed of the SAR satellite in the three-dimensional rectangular coordinate system of the station center includes: the coordinates of the ground point in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center are respectively made to be XPAnd YPThe position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The speeds of the SAR satellite in the X-axis direction and the Y-axis direction in the station center three-dimensional rectangular coordinate system are respectively VX *And VY *The two intermediate parameters are respectively lxAnd l andyif the distance from the SAR satellite to the ground is R, and the height of the ground point in the geocentric geodetic coordinate system is H, then:
Figure BDA0002020208850000033
Figure BDA0002020208850000041
optionally, the converting the coordinates of the ground point in the station center three-dimensional rectangular coordinate system into coordinates in a station center earth-fixed coordinate system to obtain the ground position of the ground point includes: let (X, Y, Z) represent the coordinates of the ground point in the geocentric geostationary coordinate system, (X)0，Y0，Z0) Representing the coordinates of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geostationary coordinate system, XPAnd YPRespectively representing the coordinates of the ground point in the X-axis direction and the Y-axis direction in the station center three-dimensional rectangular coordinate system; b is0And L0Respectively representing the latitude and longitude of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geodetic coordinate system.
X＝X0-XPsinB0cos L0-YPsin L0+H cos B0cos L0；
Y＝Y0-XPsin B0sin L0+YPcos L0+H cos B0sin L0；
Z＝Z0+XPcos B0+H sin B0。
Another aspect of the present disclosure provides a device for resolving a ground location of an SAR image, including:
the first calculation module is used for establishing a station center three-dimensional rectangular coordinate system by taking the central point of the SAR image corresponding to the ground measurement area as an original point, the meridian direction as an X axis and the normal direction perpendicular to the earth surface as a Z axis;
the second calculation module is used for calculating the coordinates of ground points corresponding to the pixel points in the SAR image in the station center three-dimensional rectangular coordinate system;
and the third calculation module is used for converting the coordinates of the ground points in the station center three-dimensional rectangular coordinate system into coordinates in a ground center and ground fixation coordinate system so as to acquire the ground positions of the ground points.
Another aspect of the present disclosure provides an electronic device including: the system comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, and is characterized in that the processor realizes each step in the on-satellite on-orbit SAR image ground position resolving method when executing the computer program.
Another aspect of the present disclosure provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps in the on-board method for on-board orbit solution of SAR image ground position.
The at least one technical scheme adopted in the embodiment of the disclosure can achieve the following beneficial effects:
the method disclosed by the embodiment of the invention strictly follows a strict model of satellite-borne SAR image positioning in the process of calculating the ground position of the SAR image, is a direct explicit resolving process, is concise and strict in calculation process, less in intermediate parameter, free from iteration, low in requirements on performance and memory of a computer, and suitable for on-board on-orbit real-time calculation.
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For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram schematically illustrating a method for resolving a ground location of an SAR image according to an embodiment of the present disclosure;
FIG. 2 schematically shows a flowchart of step 102 in a method for resolving a ground location of a SAR image according to an embodiment of the present disclosure;
FIG. 3 is a block diagram schematically illustrating a structure of a device for resolving a ground location of an SAR image according to an embodiment of the present disclosure;
fig. 4 schematically shows a block diagram of an electronic device provided by an embodiment of the present disclosure;
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
Some block diagrams and/or flow diagrams are shown in the figures. It will be understood that some blocks of the block diagrams and/or flowchart illustrations, or combinations thereof, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the instructions, which execute via the processor, create means for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.
Accordingly, the techniques of this disclosure may be implemented in hardware and/or software (including firmware, microcode, etc.). In addition, the techniques of this disclosure may take the form of a computer program product on a computer-readable medium having instructions stored thereon for use by or in connection with an instruction execution system. In the context of this disclosure, a computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the instructions. For example, the computer readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. Specific examples of the computer readable medium include: magnetic storage devices, such as magnetic tape or Hard Disk Drives (HDDs); optical storage devices, such as compact disks (CD-ROMs); a memory, such as a Random Access Memory (RAM) or a flash memory; and/or wired/wireless communication links.
Fig. 1 schematically illustrates a schematic diagram of a method for resolving a ground location of an SAR image according to an embodiment of the present disclosure.
As shown in fig. 1, a method for resolving a ground location of an SAR image according to an embodiment of the present disclosure includes the following operations:
step 101, establishing a three-dimensional rectangular coordinate system of a station center by taking a central point of the SAR image corresponding to the ground measurement area as an origin, a meridian direction as an X axis, and a normal direction perpendicular to the earth surface as a Z axis.
The SAR image corresponding to the ground measuring area refers to a ground area shot by the SAR image, and the central point of the SAR image corresponding to the ground measuring area represents the approximate central position of the ground area shot by the SAR image.
And 102, calculating coordinates of ground points corresponding to the pixel points in the SAR image in the station center three-dimensional rectangular coordinate system.
Calculating the coordinates of the ground points corresponding to the pixel points in the SAR image in the three-dimensional rectangular coordinate system of the station center comprises the following operations:
and step 1021, acquiring the position and the speed of the SAR satellite used for shooting the SAR image in the geocentric geostationary coordinate system.
The geocentric/geostationary coordinate system is a coordinate system with the geocentric as the origin and is a Cartesian coordinate system. The origin is the earth centroid, the z-axis and the earth axis are parallel and point to the north pole, the x-axis points to the intersection point of the meridian and the equator, and the y-axis is perpendicular to the xOz plane (namely the intersection point of the east longitude 90 degrees and the equator) to form a right-hand coordinate system.
According to the azimuth coordinate value y of the SAR image pixel point, the position and the speed of the SAR satellite in the geocentric geostationary coordinate system can be obtained by utilizing the on-satellite GPS receiver to measure data interpolation, wherein the azimuth coordinate value y of the SAR image pixel point corresponding to the ground point in the SAR image can be directly obtained according to the SAR image.
And step 1022, converting the position and the speed of the SAR satellite in the geocentric geostationary coordinate system into the position and the speed in the standing-center three-dimensional rectangular coordinate system.
Let the origin of the three-dimensional rectangular coordinate system of the station center be (B) in the earth center earth coordinate system0，L0，H0) The coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric coordinate system is (X)0，Y0，Z0) The coordinate of the SAR satellite in the geocentric geostationary coordinate system is (X)s，Ys，Zs) The SAR satellite has a velocity (V) in the geocentric geostationary coordinate systemX，VY，VZ) The position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The SAR satellite has a velocity (V) in the three-dimensional rectangular coordinate system of the station centerX *，VY *，VZ *) And then:
Figure BDA0002020208850000071
Figure BDA0002020208850000072
Figure BDA0002020208850000073
Figure BDA0002020208850000074
Figure BDA0002020208850000075
Figure BDA0002020208850000076
wherein, the origin of the geocentric geodetic coordinate system is the centroid of the earth,the x-axis represents longitude L, the y-axis represents latitude B, the z-axis represents height H, and the origin of the three-dimensional rectangular coordinate system of the station center is the coordinate (B) in the geocentric geodetic coordinate system0，L0，H0) Can be obtained a priori, for example, read from known digital ground model data, and the coordinates (X) of the origin of the three-dimensional rectangular coordinate system of the standing center in the geocentric coordinate system of the earth's center0，Y0，Z0) The coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric-geodetic coordinate system can be calculated, and the calculation method for converting the coordinates in the geocentric-geodetic coordinate system into the coordinates in the geocentric-geodetic coordinate system is common general knowledge in the art and is not described herein again.
And 1023, calculating the distance from the SAR satellite to the ground based on the distance coordinate value of the SAR image pixel point corresponding to the ground point in the SAR image.
The distance from the SAR satellite to the ground is made to be R, and the distance coordinate value of an SAR image pixel point corresponding to the ground in the SAR image is made to be x; the near point slant distance is r0The resolution of the slant distance is MxAnd then:
R＝r0+x·Mx；
wherein the near point is inclined distance r0The resolution M of the slopexThe SAR image acquisition method is a known parameter of satellite-borne SAR imaging, can be directly read from auxiliary data of an SAR satellite, and the distance coordinate value x of an SAR image pixel point corresponding to a ground point in an SAR image can be directly obtained according to the SAR image.
And 1024, calculating two intermediate parameters for calculating the coordinates of the ground point in the station center three-dimensional rectangular coordinate system based on the distance between the SAR satellite and the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system.
Let lx and ly denote the two intermediate parameters, R denotes the distance of the SAR satellite to the ground, λ is the radar wavelength, fDIs the Doppler center frequency, (V)X *，VY *，VZ *) Representing the speed, Zs, of the SAR satellite in the three-dimensional rectangular coordinate system of the station center*Representing the SAR satellite in three dimensions at the station centerAnd the Z-axis coordinate in the angular coordinate system, H represents the height of the ground point in the geocentric geodetic coordinate system, and then:
Figure BDA0002020208850000081
Figure BDA0002020208850000082
wherein, the wavelength λ and Doppler center frequency f of the radarDThe method is a known parameter of satellite-borne SAR imaging, can be directly read from auxiliary data of an SAR satellite, and the height H of the ground point can be directly obtained from the height H of the origin of a three-dimensional rectangular coordinate system of a station center0Or read from known digital ground model data.
And 1025, calculating coordinates of the ground point in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center based on the two intermediate parameters, the distance between the SAR satellite and the ground and the position and the speed of the SAR satellite in the three-dimensional rectangular coordinate system of the station center.
Let the coordinates of the ground point in the X-axis and Y-axis directions in the three-dimensional rectangular coordinate system of the station center be X respectivelyPAnd YPThe position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The speeds of the SAR satellite in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center are respectively VX *And VY *The two intermediate parameters are respectively lxAnd l andyand the distance from the SAR satellite to the ground is R, and the height of the ground point in the geocentric geodetic coordinate system is H, then:
Figure BDA0002020208850000091
Figure BDA0002020208850000092
step 103, converting the coordinates of the ground point in the station center three-dimensional rectangular coordinate system into coordinates in a ground center-earth-fixed coordinate system to obtain the ground position of the ground point.
Let (X, Y, Z) represent the coordinates of the ground point in the geocentric geostationary coordinate system, (X)0，Y0，Z0) Represents the coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric coordinate system, XPAnd YPRespectively representing the coordinates of the ground point in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center; b is0And L0Respectively representing the latitude and longitude of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geodetic coordinate system.
X＝X0-XPsin B0cos L0-YPsin L0+H cos B0cos L0；
Y＝Y0-XPsin B0sin L0+YPcos L0+H cos B0sin L0；
Z＝Z0+XPcos B0+H sin B0。
The coordinates of the ground point in the geocentric geostationary coordinate system obtained through the calculation in the above steps are the ground position of the ground point.
Fig. 2 schematically shows a flowchart of step 102 in a method for resolving a ground location of a SAR image according to an embodiment of the present disclosure.
In the embodiment of the disclosure, the process of calculating the ground position of the SAR image strictly follows a strict model of satellite-borne SAR image positioning, and is a direct explicit resolving process, the calculating process is simple and strict, the intermediate parameters are few, iteration is not needed, the requirements on the performance and the memory of a computer are not high, and the method is suitable for on-board on-orbit real-time calculation.
Fig. 3 schematically shows a structural block diagram of a device for resolving a ground position of an SAR image according to an embodiment of the present disclosure.
As shown in fig. 3, the device for resolving the SAR image ground position includes: a first computing module 201, a second computing module 202, and a third computing module 203.
Specifically, the first calculation module 201 is configured to establish a three-dimensional rectangular coordinate system of a station center with a central point of the SAR image corresponding to the ground measurement area as an origin, a meridian direction as an X axis, and a normal direction perpendicular to the earth surface as a Z axis;
the second calculating module 202 is configured to calculate coordinates of ground points corresponding to pixel points in the SAR image in the station center three-dimensional rectangular coordinate system;
and the third calculation module 203 is configured to convert the coordinates of the ground point in the three-dimensional rectangular coordinate system of the station center into coordinates in a geocentric geostationary coordinate system to obtain the ground position of the ground point.
It is understood that the first computing module 201, the second computing module 202, and the third computing module 203 may be combined and implemented in one module, or any one of them may be split into a plurality of modules. Alternatively, at least part of the functionality of one or more of these modules may be combined with at least part of the functionality of the other modules and implemented in one module. According to an embodiment of the present invention, at least one of the first computing module 201, the second computing module 202, and the third computing module 203 may be implemented at least partially as a hardware circuit, such as a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a system on a chip, a system on a substrate, a system on a package, an Application Specific Integrated Circuit (ASIC), or may be implemented in hardware or firmware in any other reasonable manner of integrating or packaging a circuit, or in a suitable combination of three implementations of software, hardware, and firmware. Alternatively, at least one of the first, second and third computing modules 201, 202 and 203 may be implemented at least partially as a computer program module, which when executed by a computer may perform the functions of the respective module.
Fig. 4 schematically shows a block diagram of an electronic device provided in an embodiment of the present disclosure.
As shown in fig. 4, the electronic device described in this embodiment includes: the electronic device 300 includes a processor 310, a computer-readable storage medium 320. The electronic device 300 may perform the method described above with reference to fig. 1 to enable detection of a particular operation.
In particular, processor 310 may include, for example, a general purpose microprocessor, an instruction set processor and/or related chip set and/or a special purpose microprocessor (e.g., an Application Specific Integrated Circuit (ASIC)), and/or the like. The processor 310 may also include on-board memory for caching purposes. The processor 310 may be a single processing unit or a plurality of processing units for performing the different actions of the method flows according to embodiments of the present disclosure described with reference to fig. 1.
Computer-readable storage medium 320 may be, for example, any medium that can contain, store, communicate, propagate, or transport the instructions. For example, a readable storage medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. Specific examples of the readable storage medium include: magnetic storage devices, such as magnetic tape or Hard Disk Drives (HDDs); optical storage devices, such as compact disks (CD-ROMs); a memory, such as a Random Access Memory (RAM) or a flash memory; and/or wired/wireless communication links.
The computer-readable storage medium 320 may include a computer program 321, which computer program 321 may include code/computer-executable instructions that, when executed by the processor 310, cause the processor 310 to perform a method flow such as that described above in connection with fig. 1 and any variations thereof.
The computer program 321 may be configured with, for example, computer program code comprising computer program modules. For example, in an example embodiment, code in computer program 321 may include one or more program modules, including 321A, modules 321B, … …, for example. It should be noted that the division and number of modules are not fixed, and those skilled in the art may use suitable program modules or program module combinations according to actual situations, which when executed by the processor 310, enable the processor 310 to execute the method flows described above in connection with fig. 1-2, for example, and any variations thereof.
According to an embodiment of the present invention, at least one of the first computing module 201, the second computing module 202 and the third computing module 203 may be implemented as a computer program module described with reference to fig. 4, which, when executed by the processor 310, may implement the respective operations described above.
The present disclosure also provides a computer-readable medium, which may be embodied in the apparatus/device/system described in the above embodiments; or may exist separately and not be assembled into the device/apparatus/system. The computer readable medium carries one or more programs which, when executed, implement the method according to an embodiment of the disclosure.
Those skilled in the art will appreciate that various combinations and/or combinations of features recited in the various embodiments and/or claims of the present disclosure can be made, even if such combinations or combinations are not expressly recited in the present disclosure. In particular, various combinations and/or combinations of the features recited in the various embodiments and/or claims of the present disclosure may be made without departing from the spirit or teaching of the present disclosure. All such combinations and/or associations are within the scope of the present disclosure.
While the disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Accordingly, the scope of the present disclosure should not be limited to the above-described embodiments, but should be defined not only by the appended claims, but also by equivalents thereof.

Claims (7)

1. A method for solving the ground position of an SAR image is characterized by comprising the following steps:
establishing a station center three-dimensional rectangular coordinate system by taking the central point of the SAR image corresponding to the ground measurement area as an original point, the meridian direction as an X axis and the normal direction perpendicular to the earth surface as a Z axis;
calculating the coordinates of ground points corresponding to the pixel points in the SAR image in the station center three-dimensional rectangular coordinate system;
converting the coordinates of the ground points in the station center three-dimensional rectangular coordinate system into coordinates in a ground center-to-ground solid coordinate system so as to obtain the ground positions of the ground points;
wherein the calculating the coordinates of the ground points corresponding to the pixel points in the SAR image in the station center three-dimensional rectangular coordinate system comprises:
acquiring the position and the speed of an SAR satellite for shooting the SAR image in the geocentric geostationary coordinate system;
converting the position and the speed of the SAR satellite in the geocentric geostationary coordinate system into the position and the speed in the station-centric three-dimensional rectangular coordinate system;
calculating the distance from the SAR satellite to the ground based on the distance coordinate value of the SAR image pixel point corresponding to the ground point in the SAR image;
calculating two intermediate parameters for calculating the coordinates of the ground point in the station center three-dimensional rectangular coordinate system based on the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system;
let lx and ly denote the two intermediate parameters, R denotes the distance of the SAR satellite to the ground, λ is the radar wavelength, fDIs the Doppler center frequency, (V)X *，VY *，VZ *) Representing the speed, Zs, of the SAR satellite in the three-dimensional rectangular coordinate system of the station center*Representing the Z-axis coordinate of the SAR satellite in the three-dimensional rectangular coordinate system of the station center, and H represents the height of the ground point in the geocentric geodetic coordinate system, then:
Figure FDA0002945204230000011
Figure FDA0002945204230000012
calculating coordinates of the ground point in X-axis and Y-axis directions in the station center three-dimensional rectangular coordinate system based on the two intermediate parameters, the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system;
the coordinates of the ground point in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center are respectively made to be XPAnd YPThe position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The speeds of the SAR satellite in the X-axis direction and the Y-axis direction in the station center three-dimensional rectangular coordinate system are respectively VX *And VY *The two intermediate parameters are respectively lxAnd l andyif the distance from the SAR satellite to the ground is R, and the height of the ground point in the geocentric geodetic coordinate system is H, then:
Figure FDA0002945204230000021
Figure FDA0002945204230000022
2. the method of claim 1, wherein the converting the position and velocity of the SAR satellite in the geocentric geostationary coordinate system to a position and velocity in the station-centric three-dimensional rectangular coordinate system comprises:
the coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geodetic coordinate system is (B)0，L0，H0) The coordinate of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geostationary coordinate system is (X)0，Y0，Z0) The coordinate of the SAR satellite in the geocentric geostationary coordinate system is (X)s，Ys，Zs) The SAR satellite has a velocity of (V) in the geocentric geostationary coordinate systemX，VY，VZ) The position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The SAR satellite has a speed of (V) in the three-dimensional rectangular coordinate system of the station centerX *，VY *，VZ *) And then:
Figure FDA0002945204230000023
Figure FDA0002945204230000024
Figure FDA0002945204230000025
Figure FDA0002945204230000026
Figure FDA0002945204230000027
Figure FDA0002945204230000028
3. the method of claim 1, wherein the calculating the distance from the SAR satellite to the ground based on the distance coordinate value of the SAR image pixel point corresponding to the ground point in the SAR image comprises:
the distance from the SAR satellite to the ground is R, and the distance direction coordinate of the SAR image pixel point corresponding to the ground point in the SAR imageA value of x; the near point slant distance is r0The resolution of the slant distance is MxAnd then:
R＝r0+x·Mx。
4. the method of any of claims 1 to 3 wherein said converting the coordinates of the ground points in the three-dimensional rectangular coordinates of the centroid to coordinates in the geocentric geostationary coordinates to obtain the ground location of the ground points comprises:
let (X, Y, Z) represent the coordinates of the ground point in the geocentric geostationary coordinate system, (X)0，Y0，Z0) Representing the coordinates of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geostationary coordinate system, XPAnd YPRespectively representing the coordinates of the ground point in the X-axis direction and the Y-axis direction in the station center three-dimensional rectangular coordinate system; b is0And L0Respectively representing the latitude and longitude of the origin of the three-dimensional rectangular coordinate system of the station center in the geocentric geodetic coordinate system, then:
X＝X0-XPsinB0cosL0-YPsinL0+HcosB0cosL0；
Y＝Y0-XPsinB0sinL0+YPcosL0+HcosB0sinL0；
Z＝Z0+XPcosB0+HsinB0。
5. a device for resolving a ground location of a SAR image, comprising:
the first calculation module is used for establishing a station center three-dimensional rectangular coordinate system by taking the central point of the SAR image corresponding to the ground measurement area as an original point, the meridian direction as an X axis and the normal direction perpendicular to the earth surface as a Z axis;
the second calculation module is used for calculating the coordinates of ground points corresponding to the pixel points in the SAR image in the station center three-dimensional rectangular coordinate system;
the third calculation module is used for converting the coordinates of the ground points in the station center three-dimensional rectangular coordinate system into coordinates in a ground center-to-ground fixed coordinate system so as to obtain the ground positions of the ground points;
in the second calculation module, the calculating coordinates of ground points corresponding to pixel points in the SAR image in the station center three-dimensional rectangular coordinate system includes:
acquiring the position and the speed of an SAR satellite for shooting the SAR image in the geocentric geostationary coordinate system;
converting the position and the speed of the SAR satellite in the geocentric geostationary coordinate system into the position and the speed in the station-centric three-dimensional rectangular coordinate system;
calculating the distance from the SAR satellite to the ground based on the distance coordinate value of the SAR image pixel point corresponding to the ground point in the SAR image;
calculating two intermediate parameters for calculating the coordinates of the ground point in the station center three-dimensional rectangular coordinate system based on the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system;
let lx and ly denote the two intermediate parameters, R denotes the distance of the SAR satellite to the ground, λ is the radar wavelength, fDIs the Doppler center frequency, (V)X *，VY *，VZ *) Representing the speed, Zs, of the SAR satellite in the three-dimensional rectangular coordinate system of the station center*Representing the Z-axis coordinate of the SAR satellite in the three-dimensional rectangular coordinate system of the station center, and H represents the height of the ground point in the geocentric geodetic coordinate system, then:
Figure FDA0002945204230000041
Figure FDA0002945204230000042
calculating coordinates of the ground point in X-axis and Y-axis directions in the station center three-dimensional rectangular coordinate system based on the two intermediate parameters, the distance from the SAR satellite to the ground and the position and the speed of the SAR satellite in the station center three-dimensional rectangular coordinate system;
the coordinates of the ground point in the X-axis direction and the Y-axis direction in the three-dimensional rectangular coordinate system of the station center are respectively made to be XPAnd YPThe position of the SAR satellite in the three-dimensional rectangular coordinate system of the station center is (X)s *，Ys *，Zs *) The speeds of the SAR satellite in the X-axis direction and the Y-axis direction in the station center three-dimensional rectangular coordinate system are respectively VX *And VY *The two intermediate parameters are respectively lxAnd l andyif the distance from the SAR satellite to the ground is R, and the height of the ground point in the geocentric geodetic coordinate system is H, then:
Figure FDA0002945204230000043
6. an electronic device, comprising: memory, processor and computer program stored on the memory and executable on the processor, characterized in that the processor, when executing the computer program, implements the steps of the method of resolving the ground position of SAR images according to any one of claims 1 to 4.
7. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of resolving a ground location of a SAR image according to any one of claims 1 to 4.
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