阅读说明：本技术 分布式geo sar三维形变反演多角度选取方法及装置 (Distributed GEO SAR three-dimensional deformation inversion multi-angle selection method and device ) 是由 胡程 谢煜辉 董锡超 陈志扬 李元昊 于 2021-08-12 设计创作，主要内容包括：本发明提供一种分布式GEO SAR三维形变反演多角度选取方法及装置,所述方法包括获取分布式GEO SAR系统对观测目标全部照射的空间范围内的速度、坐标、场景坐标,得到三维形变模型系数矩阵；通过各观测角度下的干涉图相位方差获得相位误差的协方差矩阵；根据所述三维形变模型系数矩阵和所述相位误差的协方差矩阵,计算所述分布式GEO SAR系统对观测目标在全部照射时间段内的测量精度系数最小定位精度系数；基于所述分布式GEO SAR系统对观测目标在全部照射时间段内的测量精度系数最小定位精度系数,进行最优组合选择。根据本发明的方案,可有效提高地表三维形变反演精度。(The invention provides a distributed GEO SAR three-dimensional deformation inversion multi-angle selection method and a device, wherein the method comprises the steps of obtaining the speed, the coordinate and the scene coordinate of a distributed GEO SAR system in a space range of all irradiation of an observation target to obtain a three-dimensional deformation model coefficient matrix; obtaining a covariance matrix of phase errors through interference pattern phase variances under each observation angle; calculating the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods according to the three-dimensional deformation model coefficient matrix and the covariance matrix of the phase error; and performing optimal combination selection on the basis of the minimum positioning precision coefficient of the measurement precision coefficient of the observation target in all the irradiation time periods by the distributed GEO SAR system. According to the scheme of the invention, the inversion precision of the three-dimensional deformation of the earth surface can be effectively improved.)

1. A distributed GEO SAR three-dimensional deformation inversion multi-angle selection method is characterized by comprising the following steps:

step S101: acquiring the speed, the coordinate and the scene coordinate of the distributed GEO SAR system in the space range of all the irradiation of the observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd unit vector of target slant distance of GEO satelliteObtaining the coefficient of the three-dimensional deformation modelA matrix Θ, where n ═ 1,2, 3;

step S102: calculating the phase variance of the interference pattern at each observation angle according to the multi-vision number N and the correlation coefficient gamma of the interference pattern, and obtaining a covariance matrix C of the phase error according to the phase variance of the interference pattern at each observation angle_Φ；

Step S103: according to the coefficient matrix theta of the three-dimensional deformation model and the covariance matrix C of the phase error_ΦCalculating the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods;

step S104: based on the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods, optimal combination selection is carried out:

the distributed GEO SAR system irradiates the whole range S of the orbit to the observation target_aIn the above, the optimal combination of three observation angles is obtained, wherein S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀And (5) carrying out measurement accuracy coefficient of three-dimensional deformation inversion.

2. The distributed GEO SAR three-dimensional deformation inversion multi-angle selection method of claim 1, wherein the coefficient matrix Θ of the three-dimensional deformation model is calculated in the following manner:

where λ is the radar wavelength, <, > represents the vector inner product.

3. The distributed GEO SAR three-dimensional deformation inversion multi-angle selection method of claim 2, characterized in that in the step S102, the covariance matrix C of the phase error_ΦIs shown as

Wherein, the phase variance of the interference pattern at each observation angleCalculated from the multi-view N and the correlation coefficient gamma of the corresponding interferogram,

4. the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method of claim 3, characterized in that the step S103 is used for calculating the measurement precision coefficient minimum positioning precision coefficient PDOP of the distributed GEO SAR system to the observation target in all the irradiation time periods_dThe method comprises the following steps:

when distinguishing the magnitude of the phase error of the interferogram generated at each observation angle,

when the magnitude of the phase error of the interferogram generated at each observation angle is not distinguished,

wherein tr (-) is the trace of the matrix.

5. The utility model provides a device is selected to three-dimensional deformation inversion multi-angle of distributing type GEO SAR, its characterized in that, the device includes:

a coefficient matrix acquisition module: the method comprises the steps of configuring to obtain the speed, the coordinate and the scene coordinate of a distributed GEO SAR system in a space range of all irradiation of an observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd unit vector of target slant distance of GEO satelliteObtaining a three-dimensional deformation model coefficient matrix theta, wherein n is 1,2 and 3;

a covariance matrix acquisition module: configured to calculate phase variance of the interferogram at each observation angle from the multi-view N and the correlation coefficient γ of the interferogram, and obtain a covariance matrix C of phase errors from the phase variance of the interferogram at each observation angle_Φ；

Precision coefficient calculation module: configured to obtain a covariance matrix C according to the three-dimensional deformation model coefficient matrix Θ and the phase error_ΦCalculating the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods;

an observation angle determining module: the optimal combination selection is carried out on the basis of the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods:

the distributed GEO SAR system irradiates the whole range S of the orbit to the observation target_aIn the above, the optimal combination of three observation angles is obtained, wherein S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀And (5) carrying out measurement accuracy coefficient of three-dimensional deformation inversion.

6. The distributed GEO SAR three-dimensional deformation inversion multi-angle selection device of claim 5, wherein the coefficient matrix Θ of the three-dimensional deformation model is calculated in the following way:

where λ is the radar wavelength, <, > represents the vector inner product.

7. The distributed GEO SAR three-dimensional deformation inversion multi-angle selection device of claim 6, wherein the covariance matrix C of the phase error_ΦIs shown as

Wherein, the phase variance of the interference pattern at each observation angleCalculated from the multi-view N and the correlation coefficient gamma of the corresponding interferogram,

8. the device of claim 7, wherein the device for selecting the distributed GEO SAR three-dimensional deformation inversion from multiple angles calculates a minimum positioning accuracy coefficient PDOP of the measurement accuracy coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods_dThe method comprises the following steps:

when distinguishing the magnitude of the phase error of the interferogram generated at each observation angle,

when the magnitude of the phase error of the interferogram generated at each observation angle is not distinguished,

wherein tr (-) is the trace of the matrix.

9. A multi-angle selection system for distributed GEO SAR three-dimensional deformation inversion comprises:

a processor for executing a plurality of instructions;

a memory to store a plurality of instructions;

wherein the instructions are used for being stored by the memory and loaded and executed by the processor to perform the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method according to any one of claims 1-4.

10. A computer-readable storage medium having stored therein a plurality of instructions; the instructions are used for loading and executing the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method according to any one of claims 1-4 by a processor.

Technical Field

The invention relates to the field of radars, in particular to a distributed GEO SAR three-dimensional deformation inversion multi-angle selection method and device.

Background

Geosynchronous orbit Synthetic Aperture Radar (GEO SAR) operates at an orbit height of about 36000km, and has fast revisit capability and continuous coverage performance. However, for the GEO SAR with a small 8-track of the intersatellite point of a medium dip angle, the GEO SAR is subjected to target scattering time decorrelation and atmospheric disturbance decorrelation in the deformation inversion application, and has small east-west direction angle difference and poor three-dimensional deformation inversion performance. The distributed GEO SAR composed of passively received slave stars is added on the basis of the single-star GEO SAR, the defects can be overcome, centimeter-millimeter-scale emergency response three-dimensional deformation measurement is realized for an observation area, and the method has important significance in disaster prevention and reduction and disaster monitoring.

However, unlike monostatic SAR, distributed GEO SAR faces the following problems in three-dimensional deformation inversion: (1) the receiving and sending platform is separately arranged, and the three-dimensional deformation inversion model and the precision analysis method of the single-base SAR fail; (2) the system has a plurality of observation angles, and the optimal observation angle cannot be selected for carrying out three-dimensional deformation inversion. Therefore, a distributed GEO SAR three-dimensional deformation inversion accuracy analysis method needs to be established, and an observation angle combination with the best inversion performance is selected. However, the existing deformation inversion method cannot solve the problems.

Disclosure of Invention

In order to solve the technical problems, the invention provides a multi-angle selection method and a multi-angle selection device for three-dimensional deformation inversion of a distributed GEO SAR (geostationary orbit synthetic aperture radar), and the method and the device are used for solving the technical problems of the distributed GEO SAR in the prior art in the aspect of three-dimensional deformation inversion.

According to a first aspect of the invention, a distributed GEO SAR three-dimensional deformation inversion multi-angle selection method is provided, which comprises the following steps:

step S101: acquiring the speed, the coordinate and the scene coordinate of the distributed GEO SAR system in the space range of all the irradiation of the observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd unit vector of target slant distance of GEO satelliteObtaining a three-dimensional deformation model coefficient matrix theta, wherein n is 1,2 and 3;

step S102: calculating the phase variance of the interference pattern at each observation angle according to the multi-vision number N and the correlation coefficient gamma of the interference pattern, and obtaining a covariance matrix C of the phase error according to the phase variance of the interference pattern at each observation angle_Φ；

Step S103: according to the coefficient matrix theta of the three-dimensional deformation model and the covariance matrix C of the phase error_ΦCalculating the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods;

step S104: based on the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods, optimal combination selection is carried out:

at the distributed GEThe total irradiation orbit range S of the O SAR system to the observation target_aIn the above, the optimal combination of three observation angles is obtained, wherein S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀And (5) carrying out measurement accuracy coefficient of three-dimensional deformation inversion.

According to a second aspect of the present invention, there is provided a distributed GEO SAR three-dimensional deformation inversion multi-angle selection device, comprising:

a coefficient matrix acquisition module: the method comprises the steps of configuring to obtain the speed, the coordinate and the scene coordinate of a distributed GEO SAR system in a space range of all irradiation of an observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd unit vector of target slant distance of GEO satelliteObtaining a three-dimensional deformation model coefficient matrix theta, wherein n is 1,2 and 3;

a covariance matrix acquisition module: configured to calculate phase variance of the interferogram at each observation angle from the multi-view N and the correlation coefficient γ of the interferogram, and obtain a covariance matrix C of phase errors from the phase variance of the interferogram at each observation angle_Φ；

Precision coefficient calculation module: configured to obtain a covariance matrix C according to the three-dimensional deformation model coefficient matrix Θ and the phase error_ΦCalculating the distributed GEO SARThe system positions the minimum measurement precision coefficient of the observation target in all the irradiation time periods;

an observation angle determining module: the optimal combination selection is carried out on the basis of the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods:

the distributed GEO SAR system irradiates the whole range S of the orbit to the observation target_aIn the above, the optimal combination of three observation angles is obtained, wherein S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀And (5) carrying out measurement accuracy coefficient of three-dimensional deformation inversion.

According to a third aspect of the present invention, there is provided a distributed GEO SAR three-dimensional deformation inversion multi-angle selection system, comprising:

a processor for executing a plurality of instructions;

a memory to store a plurality of instructions;

the instructions are stored in the memory, and loaded and executed by the processor, so that the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method is realized.

According to a fourth aspect of the present invention, there is provided a computer readable storage medium having a plurality of instructions stored therein; the instructions are used for loading and executing the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method by the processor.

According to the scheme, the method establishes a distributed GEO SAR three-dimensional deformation inversion model and a precision analysis method thereof; the method for selecting the optimal observation angle to carry out the three-dimensional deformation inversion and the criterion for evaluating the three-dimensional deformation inversion precision in the observation angle selection process are provided, and the comprehensive and visual evaluation of the three-dimensional deformation inversion precision is realized. By selecting the optimal angle combination to carry out deformation inversion, the inversion precision of the three-dimensional deformation of the earth surface can be effectively improved.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic flow chart of a distributed GEO SAR three-dimensional deformation inversion multi-angle selection method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a multi-angle selection method for three-dimensional deformation inversion according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of SAR data acquisition principles according to an embodiment of the present invention;

FIG. 4(A) is a high level diagram of a simulation scenario in accordance with one embodiment of the present invention;

FIG. 4(B) is a schematic view of the amount of deformation in the height direction according to an embodiment of the present invention;

FIG. 5(A) is a schematic diagram of simulation verification results of deformation inversion in north and south directions according to an embodiment of the present invention;

FIG. 5(B) is a schematic diagram of a simulation verification result of the east-west deformation inversion according to an embodiment of the present invention;

FIG. 5(C) is a schematic diagram of a simulation verification result of deformation inversion in the height direction according to an embodiment of the present invention;

FIG. 6 is a structural block diagram of a distributed GEO SAR three-dimensional deformation inversion multi-angle selection device according to an embodiment of the invention.

Detailed Description

First, a flow of a distributed GEO SAR three-dimensional deformation inversion multi-angle selection method according to an embodiment of the present invention is described with reference to fig. 1. As shown in fig. 1-2, the method comprises the steps of:

step S101: acquiring the speed, the coordinate and the scene coordinate of the distributed GEO SAR system in the space range of all the irradiation of the observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd unit vector of target slant distance of GEO satelliteObtaining a three-dimensional deformation model coefficient matrix theta, wherein n is 1,2 and 3;

step S102: calculating the phase variance of the interference pattern at each observation angle according to the multi-vision number N and the correlation coefficient gamma of the interference pattern, and obtaining a covariance matrix C of the phase error according to the phase variance of the interference pattern at each observation angle_Φ；

Step S103: according to the coefficient matrix theta of the three-dimensional deformation model and the covariance matrix C of the phase error_ΦCalculating the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods;

step S104: based on the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods, optimal combination selection is carried out:

the distributed GEO SAR system irradiates the whole range S of the orbit to the observation target_aTo obtain the optimal three observationsAngle combination of S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀And (5) carrying out measurement accuracy coefficient of three-dimensional deformation inversion.

As shown in fig. 3, the step S101: acquiring the speed, the coordinate and the scene coordinate of the distributed GEO SAR system in the space range of all the irradiation of the observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd unit vector of target slant distance of GEO satelliteObtaining a three-dimensional deformation model coefficient matrix theta, wherein n is 1,2,3, wherein:

the coefficient matrix theta of the three-dimensional deformation model is calculated in the following mode:

where λ is the radar wavelength, <, > represents the vector inner product.

The specific principle of establishing the three-dimensional deformation inversion model is as follows.

Suppose S_A1、S_A2And S_A3Respectively representing equivalent aperture center positions of the distributed GEO SAR obtained under three different observation angles, and the corresponding measured deformation interference phases are phi₁、Φ₂And phi₃And then the established three-dimensional deformation inversion model based on multi-angle observation is expressed as

Φ＝Θd (3)

Wherein phi is (phi)₁,Φ₂,Φ₃)^TFor the phase measurement vector, theta is the coefficient matrix of the three-dimensional deformation model, and d is (d)_N,d_E,d_U)^TRepresenting the three-dimensional deformation information of the earth's surface in a rectangular coordinate system, d_NIs the north-south direction deformation, d_EIs the east-west direction variable, d_UIs the vertical deformation, and T is the transposition.

The deformation field measured by D-InSAR (Differential Synthetic Aperture Radar, D-InSAR) is not the true vertical, east-west, and south-north deformations of the earth surface, but the projection of the earth surface deformation field in the direction of the satellite sight line, so that the sensitive direction and the observation deformation amount of the distributed GEO SAR to the deformation measurement of the target scene area at different observation angles need to be determined, which is not considered in the existing deformation inversion research.

Definition of S_TAnd S_RTransmitter and receiver positions, S, respectively_AIs the equivalent aperture center position. P is the position of the scene observation target, and subscripts 1 and 2 represent the two previous and subsequent measurements, respectively. Representation of the interference phase as

Wherein

Carrying out Taylor first-order expansion on the formula (5) to obtain

In the case where formula (6) is substituted for formula (4), the separable deformation phase is represented by

The deformation phase is derived from the deformation

Wherein beta isAndi.e. a dihedral angle.

From equation (8), the direction most sensitive to deformation, i.e., the measurement direction, can be found

And (3) combining the formulas (3) and (8) to obtain a three-dimensional deformation model coefficient matrix theta expression (2).

The step S102: calculating the phase variance of the interference pattern at each observation angle according to the multi-vision number N and the correlation coefficient gamma of the interference pattern, and obtaining a covariance matrix C of the phase error according to the phase variance of the interference pattern at each observation angle_ΦWherein:

the correlation coefficient γ can be assumed based on the influence of time of deformation measurement and RFI decorrelation.

Generally, the coverage angle range of the GEO SAR system to the target is large, and there is no overlap between GEO SAR imaging sub-apertures at different observation angles. Therefore, these sub-aperture data can be considered independent, and the interferograms obtained at different observation angles are also uncorrelated. At this time, the covariance matrix C_ΦThe elements on the middle non-diagonal are all 0, C_ΦIs only determined by the elements on the diagonal and expressed as

Wherein, the phase variance of the interference pattern at each observation angleCalculated from the multi-view N and the correlation coefficient gamma of the corresponding interferogram,

the step S103: according to the coefficient matrix theta of the three-dimensional deformation model and the covariance matrix C of the phase error_ΦCalculating the minimum positioning precision coefficient PDOP of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods_dWherein:

in this embodiment, the minimum positioning accuracy coefficient PDOP of the measurement accuracy coefficient of the distributed GEO SAR system for the observation target in all the irradiation time periods is calculated by distinguishing the phase error magnitude of the interferogram generated at each observation angle from the phase error magnitude of the interferogram generated at each observation angle_dIn a different manner, the first and second electrodes are,

the magnitude of the phase error of the generated interferogram at each observation angle is distinguished,

without distinguishing the magnitude of the phase error of the generated interferogram at each observation angle,

wherein tr (-) is the trace of the matrix,

in this embodiment, a concept of a minimum positioning Precision coefficient (PDOP) is introduced to evaluate comprehensive performance of three-dimensional deformation measurement Precision of a scene target under different sub-aperture data combinations. According toClassical PDOP definition, defining the measurement accuracy factor PDOP for three-dimensional deformation_dIs shown as

Wherein, Λ²The sum of the variances of the three-dimensional deformation is represented, and the comprehensive precision of the three-dimensional deformation inversion is represented;the sum of the phase variances of the three interferograms is shown.

Obtaining an estimate of the three-dimensional deformation quantity using the least squares method for equation (3)Is shown as

Wherein, C_ΦIs a covariance matrix of the phase error.

Estimating the covariance matrix of the obtained deformation quantity according to equation (14)Is shown as

The variance vector of the three-dimensional deformation obtained by the multi-angle observation method is expressed as

PDOP obtained by substituting formula (9) and formula (16) for formula (13)_dIs expressed as

If the phase error of the generated interferogram under each sub-aperture is not distinguished, the above formula can be simplified into

The step S104: based on the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods, optimal combination selection is carried out:

the distributed GEO SAR system irradiates the whole range S of the orbit to the observation target_aIn the above, the optimal combination of three observation angles is obtained, wherein S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀A measurement accuracy coefficient for performing three-dimensional deformation inversion, wherein:

the distributed GEO SAR system is stable to phase noise of an interferogram generated by sub-apertures selected by an observation target in all illumination time periods, and the accuracy of three-dimensional deformation inversion mainly depends on the space geometric relationship of the sub-apertures used for the three-dimensional deformation inversion, namely the selection of observation angle positions. Therefore, the optimal observation angle position data needs to be searched in the space range of the distributed GEO SAR system for observing all the irradiation of the target to perform three-dimensional deformation inversion, so that the comprehensive accuracy of the inverted three-dimensional deformation reaches the best. Considering the minimum positioning precision coefficient of the measurement precision coefficient of the observation target in all the irradiation time periods based on the distributed GEO SAR system, carrying out optimal combination selection,

since the trajectory of GEO SAR is very curved and complex, it is difficult to directly obtain the analytical solution of equation (1). Therefore, the whole irradiation orbit range S of the distributed GEO SAR system to the target can be realized_aAnd setting step quantity or further interpolating and refining step intervals according to the application precision requirement, and obtaining the optimal combination of the three observation angles by utilizing a search algorithm.

The distributed GEO SAR three-dimensional deformation inversion multi-angle selection method is described in combination with specific parameters.

In this example, we consider a distributed GEO SAR system consisting of a master satellite with transceiving capabilities and a slave satellite that is only passively receiving signals. The number of satellite orbits is shown in table 1, and the platform parameters are shown in table 2. At least three pairs of SAR image pairs are needed for realizing SAR three-dimensional deformation inversion, wherein two pairs of image pairs are obtained by irradiating the same region for multiple times by a main satellite, one pair of image pairs are obtained by transmitting by the main satellite and receiving and irradiating the same region by a satellite, and the SAR data obtaining principle is shown in figure 3.

The scene center of SAR imaging is located at the east longitude 104.4 degrees and the north latitude 36.9 degrees. A pyramid with a base of 1km multiplied by 1km and a height of 1m is arranged in the middle of the scene. The top of the pyramid has a height direction deformation amount of 5cm, and the height direction deformation amount linearly descending along the topographic variation gradient direction of the pyramid exists from the top of the pyramid to the bottom of the pyramid. There is no deformation in the east-west direction and the north-south direction. Assuming a time base of 1 day for deformation measurement, the satellite images the scene, each image being 120 pixels by 120 pixels with a pixel spacing of 10 m. The three-dimensional image and the amount of height distortion of the simulated scene are shown in fig. 4(a) -4 (B).

TABLE 1

Number of tracks	Master star	Slave star
			Semi-major axis (km)	42164	42164
Eccentricity of a rotor	0	0
			Inclination angle (°)	16	16
Amplitude angle of the near place (°)	0	0
			Ascending crossing point Chijing Longitude (°)	88	127.8
Mean angle of approach (°)	0	0

TABLE 2

Platform parameters	Numerical value
		Wavelength (m)	0.24
Bandwidth (MHz)	60
		Pulse width (mus)	20
Pulse repetition frequency (Hz)	50
		Synthetic aperture time(s)	1000

Firstly, according to step 1, information such as speed, coordinates, scene coordinates and the like in a space range in which the distributed GEOSAR system irradiates all the observation targets is obtained (here, the information is obtained after the satellites and the target positions are set through a software Satellite Tool Kit). According to the scene center P₀Calculating unit vectors of north, east and vertical directionsCalculating the equivalent aperture center position S of the differential interferometry at the track aperture center time corresponding to each observation angle_AnN is 1,2,3, calculating the angle beta of the aperture center at the moment_nN is a unit vector of 1,2,3 and GEO satellite to target slant rangeAnd n is 1,2 and 3, and the three-dimensional deformation model coefficient matrix theta is obtained.

Step 2, interference pattern phase variance under each observation angle is obtained through equivalent multi-vision N and correlation coefficient gamma of the interference patternn is 1,2,3, and a covariance matrix C of the phase error is obtained_ΦWhere N is 1, the correlation coefficient γ is 0.8.

Step 3, obtaining a coefficient matrix theta of the three-dimensional deformation model and a covariance matrix C of the phase error_ΦThe measurement accuracy coefficient PDOP is calculated by using equation (12) without distinguishing the magnitude of the phase error of the interferogram generated under each sub-aperture_dThe value is obtained.

Step 4, using the optimal angle combination selection method under the PDOP criterion,

spatial range S of all irradiation of target in distributed GEO SAR system_aAnd setting the step amount to be 600s, obtaining the optimal combination of three observation angles by utilizing a search algorithm, wherein true paraxial point angles corresponding to the aperture center position are respectively 9.9 degrees, 89.4 degrees and 124.1 degrees.

According to the selection of the optimal three observation angles, then the differential interference processing is performed on the scene at the track positions corresponding to the three angles, and fig. 5(a) -5(C) show the final three-dimensional deformation inversion result. It can be seen that the height direction has a significant deformation, which is consistent with the height direction deformation set.

Meanwhile, the comparison result of inversion accuracies of two groups of deformation, in which the selection method is used and the selection method is not used, namely the combination of three observation angles is selected at will, and true paraxial points corresponding to the aperture center positions are 39.7 degrees, 121.7 degrees and 86.9 degrees respectively, is shown in table 3, which proves the effectiveness of the method.

TABLE 3 inversion accuracy evaluation of three-dimensional deformation

	Using a selection method	Without using a selection method
			North-south direction (cm)	0.7	6.8
East-west direction (cm)	1.5	1.0
			Height direction (cm)	3.9	2.5
PDOPd	6.2	21.6

The embodiment of the invention further provides a distributed GEO SAR three-dimensional deformation inversion multi-angle selection device, as shown in FIG. 6, the device comprises:

a coefficient matrix acquisition module: the method comprises the steps of configuring to obtain the speed, the coordinate and the scene coordinate of a distributed GEO SAR system in a space range of all irradiation of an observation target; wherein the center of the scene is marked as P₀According to the scene center P₀Calculating unit vectors of north, east and vertical directionsSelecting any three observation angles, and obtaining the equivalent aperture center position S of the differential interferometry at the track aperture center moment corresponding to each observation angle_AnCalculating the double base angle beta of the track aperture center time_nAnd GEO satellite to targetUnit vector of slope distanceObtaining a three-dimensional deformation model coefficient matrix theta, wherein n is 1,2 and 3;

a covariance matrix acquisition module: configured to calculate phase variance of the interferogram at each observation angle from the multi-view N and the correlation coefficient γ of the interferogram, and obtain a covariance matrix C of phase errors from the phase variance of the interferogram at each observation angle_Φ；

Precision coefficient calculation module: configured to obtain a covariance matrix C according to the three-dimensional deformation model coefficient matrix Θ and the phase error_ΦCalculating the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods;

an observation angle determining module: the optimal combination selection is carried out on the basis of the minimum positioning precision coefficient of the measurement precision coefficient of the distributed GEO SAR system to the observation target in all the irradiation time periods:

the distributed GEO SAR system irradiates the whole range S of the orbit to the observation target_aIn the above, the optimal combination of three observation angles is obtained, wherein S_A1,S_A2,S_A3Equivalent aperture center position, P, of differential interferometry at the time of the center of the orbit aperture corresponding to each observation angle₀To observe the center of the scene, PDOP_d(S_A1,S_A2,S_A3,P₀) For distributed SAR systems at S_A1,S_A2,S_A3Position pair P₀And (5) carrying out measurement accuracy coefficient of three-dimensional deformation inversion.

The embodiment of the invention further provides a distributed GEO SAR three-dimensional deformation inversion multi-angle selection system, which comprises:

a processor for executing a plurality of instructions;

a memory to store a plurality of instructions;

the instructions are stored in the memory, and loaded and executed by the processor, so that the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method is realized.

The embodiment of the invention further provides a computer readable storage medium, wherein a plurality of instructions are stored in the storage medium; the instructions are used for loading and executing the distributed GEO SAR three-dimensional deformation inversion multi-angle selection method by the processor.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

In the embodiments provided in the present invention, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions in actual implementation, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.

The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a physical machine server, or a network cloud server, etc., and needs to install a Ubuntu operating system) to perform some steps of the method according to various embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are still within the scope of the technical solution of the present invention.