Atmospheric compensation method and apparatus for ground-based synthetic aperture radar, electronic device, and storage medium

Abstract

Atmospheric compensation method and apparatus for a ground-based synthetic aperture radar, an electronic device, and a storage medium. The method comprises: acquiring a two-dimensional radar multiple scattering image sequence of a target monitored area by means of a ground-based synthetic aperture radar, so as to acquire a first permanent scatterer (PS) point set (S110); on the basis of a preset atmospheric parameter model and a PS point interference phase of the first PS point set, performing atmospheric compensation on the PS point interference phase by means of an estimated atmospheric error phase (S120); determining a residual phase threshold and an accumulated deformation threshold, so as to screen the first PS point set to obtain a second PS point set (S130); and returning to execute the operation of performing atmospheric compensation on the PS point interference phase by means of the estimated the atmospheric error phase to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds a preset variation threshold (S140).

Description

Ground-based synthetic aperture radar atmospheric compensation method, device, electronic equipment and storage medium

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 11, 2023, with application number 202310841209.X. The entire contents of this application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of radar technology, and for example, to a method, device, electronic device, and storage medium for atmospheric compensation of a ground-based synthetic aperture radar. Background Art

[0003] Surface deformation is the direct cause of many major disasters, making real-time monitoring crucial. By employing effective monitoring methods to accurately acquire deformation information, disasters can be predicted in advance, minimizing or avoiding technical and economic losses. Slope deformation monitoring radar plays a significant role in surface deformation monitoring. Among these, localized, close-range measurements using ground-based synthetic aperture radar (GB-SAR) are suitable for small-scale monitoring, offering short measurement cycles and high accuracy. However, as the observation range expands in azimuth, the in-scene environment becomes more complex, and the impact of atmospheric changes, in particular, cannot be ignored. Consequently, atmospheric phase correction has become a critical issue that ground-based deformation monitoring radars must address.

[0004] GB-SAR atmospheric correction methods based on function models typically assume that atmospheric effects are strongly spatially correlated, that is, that the atmosphere is spatially uniform. In this case, atmospheric phase compensation is achieved using parameterized modeling methods using the interferometric phase of stable permanent scatterers (PS). However, the accuracy of atmospheric estimation is strongly coupled to the quality of the PS points. If a large number of deformed PS points are used as sample points in estimating atmospheric phase errors, this will inevitably lead to biased atmospheric phase estimation, which in turn affects the precision and accuracy of deformation inversion. However, in actual mine slope deformation monitoring applications, due to the large-scale, slow deformation caused by construction, most target points in the area exhibit characteristics similar to stable PS points, and are therefore identified as PS points for atmospheric phase estimation and deformation inversion. This ultimately leads to biased atmospheric phase estimation and affects deformation inversion accuracy.

[0005] The related technology has the following defects:

[0006] Most of the target points in the slowly deforming area will show characteristics similar to those of stable PS points, and thus be identified as PS points to participate in atmospheric phase estimation and deformation inversion, which will eventually lead to atmospheric phase estimation deviation and affect the deformation inversion accuracy.

[0007] Summary of the Invention

[0008] The present application provides a ground-based synthetic aperture radar atmospheric compensation method, device, electronic device and storage medium to ensure that the PS points involved in atmospheric phase estimation have high stability, improve the accuracy of atmospheric estimation, and thus improve the deformation inversion accuracy of the monitored area.

[0009] According to one aspect of the present application, a method for atmospheric compensation of a ground-based synthetic aperture radar is provided, the method comprising:

[0010] Acquire a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and obtain a first PS point set from the two-dimensional radar complex scattering image sequence;

[0011] According to a preset atmospheric parameter model and the PS point interferometric phase of the first PS point set, atmospheric compensation is performed on the PS point interferometric phase by estimating the atmospheric error phase to obtain an atmospheric compensation residual phase;

[0012] determining a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and screening the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set;

[0013] According to the PS point interference phase of the second PS point set, the operation of atmospheric compensation for the PS point interference phase is performed by estimating the atmospheric error phase to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds the preset change threshold.

[0014] According to another aspect of the present application, a ground-based synthetic aperture radar atmospheric compensation device is provided, the device comprising:

[0015] A first PS point set acquisition module is configured to acquire a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and acquire a first PS point set from the two-dimensional radar complex scattering image sequence;

[0016] an atmospheric compensation residual phase acquisition module, configured to perform atmospheric compensation on the PS point interferometric phase by estimating the atmospheric error phase based on a preset atmospheric parameter model and the PS point interferometric phase of the first PS point set, thereby obtaining an atmospheric compensation residual phase;

[0017] a second PS point set acquisition module, configured to determine a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and to filter the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set;

[0018] The atmospheric compensation operation return execution module is configured to return and execute the operation of performing atmospheric compensation on the PS point interference phase by estimating the atmospheric error phase according to the PS point interference phase of the second PS point set to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds a preset change threshold.

[0019] According to another aspect of the present application, an electronic device is provided, comprising:

[0020] at least one processor; and

[0021] a memory communicatively connected to the at least one processor; wherein,

[0022] The memory stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the ground-based synthetic aperture radar atmospheric compensation method described in any embodiment of the present application.

[0023] According to another aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the ground-based synthetic aperture radar atmospheric compensation method described in any embodiment of the present application when executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a flow chart of a ground-based synthetic aperture radar atmospheric compensation method provided in Example 1 of the present application;

[0025] FIG2a is a flow chart of another ground-based synthetic aperture radar atmospheric compensation method provided in Example 2 of the present application;

[0026] FIG2 b is an application flow chart of a ground-based synthetic aperture radar atmospheric compensation method provided in Example 2 of the present application;

[0027] FIG3 is a schematic structural diagram of a ground-based synthetic aperture radar atmospheric compensation device provided in Example 3 of the present application;

[0028] FIG4 is a schematic diagram of the structure of an electronic device for implementing the ground-based synthetic aperture radar atmosphere compensation method according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0030] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. The numbers used in this way can be interchanged where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units listed, but may include other steps or units that are not listed or that are inherent to these processes, methods, products or devices.

[0031] Example 1

[0032] Figure 1 is a flow chart of a ground-based synthetic aperture radar atmospheric compensation method provided in Example 1 of the present application. This embodiment is applicable to monitoring ground surface deformation. The method can be performed by a ground-based synthetic aperture radar atmospheric compensation device, which can be implemented in hardware and / or software and can be configured in a server with data processing capabilities. As shown in Figure 1, the method includes the following steps.

[0033] S110 , obtaining a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and obtaining a first PS point set from the two-dimensional radar complex scattering image sequence.

[0034] The target monitoring area may refer to a surface area monitored by a ground-based synthetic aperture radar. The first PS point set may be a stable PS point set obtained after a first-stage screening of the two-dimensional radar complex scattering image sequence based on the two-dimensional radar complex scattering image sequence and the PS technology, i.e., the first PS point set.

[0035] For example, the original echo of the target monitoring area can be obtained by ground-based synthetic aperture radar, and the original echo can be processed by radar imaging algorithm to obtain a two-dimensional radar complex scattering image sequence. k}(k=1, ..., K) represents a two-dimensional radar complex scattering image sequence, wherein k represents a scanning sequence number of the two-dimensional radar complex scattering image.

[0036] In one optional embodiment, obtaining a first PS point set from a two-dimensional radar complex scattering image sequence may include: determining an average correlation coefficient of each pixel in the two-dimensional radar complex scattering image sequence, an average relative amplitude of each pixel in the two-dimensional radar complex scattering image sequence, and an amplitude deviation of a time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence; selecting pixels from the two-dimensional radar complex scattering image sequence whose average correlation coefficient is greater than or equal to a preset average correlation coefficient threshold as a first candidate PS point set; selecting pixels from the first candidate PS point set whose average relative amplitude is greater than or equal to a preset average relative amplitude threshold as a second candidate PS point set; and selecting pixels from the second candidate PS point set whose amplitude deviation is less than or equal to a preset amplitude deviation threshold as the first PS point set. The pixel may be one or more pixels.

[0037] Optionally, determining an average correlation coefficient of each pixel point in the two-dimensional radar complex scattering image sequence, an average relative amplitude of each pixel point in the two-dimensional radar complex scattering image sequence, and an amplitude deviation of a time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence may include:

[0038] Based on a two-dimensional radar complex scattering image sequence, a primary radar complex scattering image, an auxiliary radar complex scattering image, an amplitude value of each pixel, and an amplitude time series of each pixel are obtained; wherein the primary radar complex scattering image and the auxiliary radar complex scattering image are any two adjacent images in the two-dimensional radar complex scattering image sequence; based on the primary radar complex scattering image and the auxiliary radar complex scattering image, a correlation coefficient of the target pixel is determined; based on multiple correlation coefficients of the target pixel in the two-dimensional radar complex scattering image sequence, an average correlation coefficient of each target pixel is determined; based on the amplitude value of each pixel, an amplitude mean of the target pixel in the two-dimensional radar complex scattering image sequence and an average amplitude mean of all target pixels are determined; based on the amplitude mean and the average amplitude mean, an average relative amplitude of each target pixel is determined; based on the amplitude time series of each pixel, a standard deviation and a mean of the amplitude time series of each pixel are determined; and based on the standard deviation and the mean, an amplitude dispersion of the time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence is determined. The correlation coefficient can be one or more.

[0039] In order to understand the above method of obtaining the first PS point set, the process can be expressed as follows:

[0040] Step 1: From {I k Two adjacent frame images are extracted from}(k=1,…,K) as the primary radar complex scattering image and the auxiliary radar complex scattering image. The correlation coefficient γ is calculated based on the primary radar complex scattering image and the auxiliary radar complex scattering image, and the formula is as follows: Wherein, represents the correlation coefficient of pixel point (i, j), * represents the complex conjugate, and w1 and w2 represent half of the sliding window length of the two dimensions of the radar complex scattering image matrix, respectively.

[0041] The image sequence of length K {I k}The correlation coefficient sequence matrix {γ k}(k=1,…,K-1), and then the average correlation coefficient can be obtained The formula is:

[0042] Set the average correlation coefficient threshold T1 to filter out The pixel points of are taken as PS points, thereby obtaining the first candidate PS point set. Among them, T1 can be set to 0.9.

[0043] Step 2: Assume that the two-dimensional radar complex scattering image I k The dimension is M*N, and the complex scattering image value corresponding to the pixel point (i, j) can be expressed as I k (i, j) = A k (i, j)exp[1j*θ(i, j)], where A k (i, j) and θ(i, j) represent the amplitude and phase of pixel (i, j) in the k-th frame of the two-dimensional radar complex scattering image, respectively. 1j represents the complex unit j. θ(i, j) represents the phase of pixel (i, j).

[0044] Then the image sequence of length K {I k The average relative amplitude of each pixel (i, j) can be Calculation. Among them, Represents the amplitude mean of pixel (i, j) in the K-frame sequence of two-dimensional radar complex scattering images Represents the average value of the amplitude of all pixels,

[0045] Set the average relative amplitude threshold T2 and filter out the first candidate PS points. PS points of , thereby obtaining the second candidate PS point set. Among them, T2 can be set to 5.

[0046] Step 3: Calculate the amplitude deviation D of the time series complex scattering image A , the formula is as follows: Among them, δ A Represents the standard deviation of the pixel amplitude time series, m A The mean of the pixel amplitude time series.

[0047] Set the amplitude deviation threshold T3 and select D from the second candidate PS point set. A The first PS point set is obtained by selecting PS points with values ​​less than or equal to T3, where T3 can be set to 0.1.

[0048] S120 , performing atmospheric compensation on the PS point interference phase by estimating the atmospheric error phase according to the preset atmospheric parameter model and the PS point interference phase of the first PS point set, to obtain an atmospheric compensation residual phase.

[0049] In this embodiment, the preset atmospheric parameter model may be a binary second-order atmospheric parameter model including distance and elevation difference.

[0050] The following is a method for constructing a preset atmospheric parameter model and calculating the optimal parameters:

[0051] Step 1: The interferometric phase of the ground-based synthetic aperture radar target point can be expressed as: φ = φ def +φ atm +φ noise , where φ represents the interference phase of the target point, φ def Represents the deformation phase of the target point, φ def is a type of error, indicating the error caused by the phase interferometry algorithm, φ atm represents the atmospheric phase, φ noise In the actual information processing process, the noise phase φ noise Usually, spatial filtering algorithms can be used to effectively eliminate the interference phase of the target point. Therefore, the interference phase of the target point can be approximated as follows: φ = φ def +φ atm .

[0052] Step 2: Construct a binary second-order atmospheric parameter model including distance and elevation difference, as shown in the following formula: Among them, φ atm represents the atmospheric error phase, λ represents the wavelength of the transmitted signal of the ground-based synthetic aperture radar, r represents the distance between the ground-based synthetic aperture radar and the target point in the target monitoring area, h represents the elevation difference between the target point and the ground-based synthetic aperture radar in the target monitoring area, β0 represents a constant term, β1 represents a coefficient related to the first power of r, β2 represents a coefficient related to the second power of r, β3 represents a coefficient related to the first power of h, β4 represents a coefficient related to the second power of h, and β5 represents a coefficient related to the first power of r and the first power of h.

[0053] Step 3: For high-quality and stable PS points, their deformation phase can be approximated to 0. Therefore, the interference phase of high-quality and stable PS points is approximately the atmospheric phase. If there are n PS points in the target monitoring area, a set of simultaneous equations φ = Xβ + ε for the atmospheric phase, distance, and elevation difference can be established.

[0054] Among them, φ=[φ1,φ2,…,φ n ] T , β=[β0,β1,…,β5] T ,ε=[ε0,ε1,…,ε n ] T φ represents the n×1 dimensional vector formed by the interference phase of n unwrapped PS points; X represents the n×6 dimensional vector formed by the constant 1 and the n PS distance and elevation differences; β represents the 6×1 dimensional vector to be estimated, and ε represents the n×1 dimensional vector formed by the phase error. β is solved using least squares. Then the estimated value of the atmospheric error phase is r1 represents the distance between the radar and the first monitoring point. PS distance represents the distance to the PS point.

[0055] S130 , determining a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and screening the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set.

[0056] S140. Return the atmospheric compensation operation for the PS point interference phase by estimating the atmospheric error phase according to the PS point interference phase of the second PS point set to obtain a new residual phase threshold, until the ratio of the new residual phase threshold to the residual phase threshold exceeds the preset change threshold.

[0057] The technical solution of the embodiment of the present application is to obtain a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and obtain a first PS point set from the two-dimensional radar complex scattering image sequence; according to a preset atmospheric parameter model and the PS point interference phase of the first PS point set, the PS point interference phase is atmospherically compensated by estimating the atmospheric error phase to obtain an atmospheric compensated residual phase; a residual phase threshold and a cumulative deformation threshold are determined for the first PS point set based on the atmospheric compensated residual phase, and the first PS point set is screened according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set; according to the PS point interference phase of the second PS point set, an operation of atmospheric compensation for the PS point interference phase by estimating the atmospheric error phase is performed to obtain a new residual phase threshold, until the ratio of the new residual phase threshold to the residual phase threshold exceeds the preset change threshold. This solves the problem that most target points in the slowly deforming area that present similar characteristics to the stable PS points participate in atmospheric phase estimation and deformation inversion, resulting in atmospheric phase estimation deviation and affecting the deformation inversion accuracy. It ensures that the PS points participating in the atmospheric phase estimation have high stability, improves the accuracy of atmospheric estimation, and thereby improves the deformation inversion accuracy of the monitoring area.

[0058] Example 2

[0059] FIG2a is a flow chart of another ground-based synthetic aperture radar atmospheric compensation method provided in Example 2 of the present application. This embodiment, based on the above embodiment, illustrates the operation S120. As shown in FIG2a, the method includes the following steps.

[0060] S210 , obtaining a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and obtaining a first PS point set from the two-dimensional radar complex scattering image sequence.

[0061] S220 . Extracting an interference phase image sequence according to a two-dimensional radar complex scattering image sequence.

[0062] For example, from {I k}(k=1, ..., K) are extracted as the main radar complex scattering image and the auxiliary radar complex scattering image for interference processing (adjacent frame interference processing is a typical synthetic aperture radar (Synthetic Aperture Radar, SAR) image interference processing method listed in this processing flow, but is not limited to this method), the auxiliary image is complex conjugated and multiplied with the main image, and the main value phase is obtained to obtain the interference phase map sequence {I in}, Wherein, * represents the complex conjugate operator, and Ang represents taking the main phase value.

[0063] S230 , obtaining the PS point interference phase of the first PS point set according to the interference phase pattern sequence.

[0064] S240 , performing unwrapping processing on the PS point interference phase to obtain the unwrapped PS point interference phase.

[0065] In this embodiment, the interferometric synthetic aperture radar (InSAR) phase unwrapping algorithm (such as the branch cutting method, the quality-guided graph method, the minimum network cost flow method, etc.) can be used to perform two-dimensional spatial unwrapping on the unwrapped PS point interference phase to obtain the unwrapped PS point interference phase.

[0066] S250: Solve the atmospheric model parameters of the preset atmospheric parameter model using the least squares method to obtain estimated atmospheric model parameters.

[0067] S260 , estimating the atmospheric error phase based on the estimated atmospheric model parameters and the unwrapped PS point interference phase.

[0068] For example, for the unwrapped PS point interferometric phase, according to the preset atmospheric parameter model and the construction method for calculating the optimal parameters provided in S120, the following results can be obtained: and

[0069] Among them, φ k，m represents the unwrapped PS interferometric phase sample vector used for the mth atmospheric phase iterative estimation after unwrapping the PS interferometric phase of the kth frame; X k，m represents an n×6-dimensional vector consisting of a constant 1 and n PS distances and elevation differences; represents the estimated atmospheric model parameters, represents the estimated atmospheric phase error.

[0070] S270 , performing atmospheric compensation processing on the unwrapped PS point interferometric phase using the atmospheric error phase to obtain an atmospheric compensation residual phase.

[0071] In this embodiment, the atmospheric compensation residual phase can be expressed as

[0072] S280 , determining a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and screening the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set.

[0073] In an optional embodiment, determining the residual phase threshold and the cumulative deformation threshold for the first PS point set based on the atmospheric compensation residual phase may include: determining the mean and standard deviation of the deformation values ​​of the PS points corresponding to the atmospheric compensation residual phase based on the atmospheric compensation residual phase, and determining the single-frame deformation image after the atmospheric compensation of the PS point interference phase; determining the residual phase threshold based on the mean, standard deviation and preset single-frame deformation threshold coefficient of the PS point deformation value; constructing a short-time deformation image sequence based on the single-frame deformation image, summing the short-time deformation image sequence to obtain a short-time cumulative image, and calculating the mean and variance of the corresponding values ​​of the PS points in the short-time cumulative image; determining the cumulative deformation threshold based on the mean, variance and preset cumulative deformation threshold coefficient of the corresponding values ​​of the PS points in the short-time cumulative image.

[0074] The following describes the process of obtaining the second PS point set:

[0075] According to the atmospheric compensation residual phase obtained from S270 Then the single-frame deformation image corresponding to the k-th frame interference phase after atmospheric compensation Expressed as Where λ represents the wavelength of the transmitted signal of the ground-based synthetic aperture radar.

[0076] calculate The sample mean and standard deviation corresponding to the deformation value of the PS point: Among them, Mean means calculating the sample mean, and Std means calculating the sample standard deviation.

[0077] Set the residual phase threshold: Among them, T θ Indicates the preset single frame deformation threshold coefficient, which can be set to 3. According to the residual phase threshold For a single frame deformed image The PS points in the filter are selected if Then the PS point needs to be removed from the PS point set and no longer participates in the atmosphere estimation, but still participates in the deformation inversion. The above removal process traverses the PS point set.

[0078] Based on single-frame deformation image Can construct short-time deformation image sequences Sum the short-time deformation image sequence to obtain the short-time cumulative image I sum , Calculate PS point in image I sum The sample mean and variance of the corresponding values ​​in are:

[0079] Set the cumulative deformation threshold: T L =I mean +T0·I std , where T0 represents the preset cumulative deformation threshold coefficient, which can be set to 2. L represents the length of the image sequence, that is, the total number of frames. L Filter the cumulative deformation value of PS point, if |I sum (i,j)|≥T L , then the PS point needs to be removed from the PS point set and no longer participates in the atmosphere estimation, but still participates in the deformation inversion. The above removal process traverses the PS point set.

[0080] S290. Return the atmospheric compensation operation on the PS point interference phase by estimating the atmospheric error phase according to the PS point interference phase of the second PS point set to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds the preset change threshold.

[0081] Use the PS points removed in step S260 to re-estimate the atmospheric phase error, calculate the atmospheric compensation residual phase after single-frame compensation, obtain a new residual phase threshold, and determine whether it meets the requirements. If the conditions are met, the atmospheric compensation operation for the PS point interferometric phase is repeated by estimating the atmospheric error phase. If not, the iteration is terminated, and the final single-frame deformed image is obtained. Where 0 < N0 ≤ 1, N0 represents the preset change threshold, which can be set to 0.95.

[0082] The technical solution of the embodiment of the present application is to obtain a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and obtain a first PS point set from the two-dimensional radar complex scattering image sequence; extract an interference phase map sequence according to the two-dimensional radar complex scattering image sequence; obtain the PS point interference phase of the first PS point set according to the interference phase map sequence; unwrap the PS point interference phase to obtain the unwrap PS point interference phase; use the least squares method to solve the atmospheric model parameters of the preset atmospheric parameter model to obtain the estimated atmospheric model parameters; estimate the atmospheric error phase according to the estimated atmospheric model parameters and the unwrap PS point interference phase; use the atmospheric error phase to perform atmospheric compensation on the unwrap PS point interference phase to obtain the atmospheric compensation residual phase; The residual phase threshold and the cumulative deformation threshold are determined for the first PS point set, and the first PS point set is screened according to the residual phase threshold and the cumulative deformation threshold to obtain the second PS point set; according to the PS point interference phase of the second PS point set, the atmospheric compensation operation of the PS point interference phase is performed by estimating the atmospheric error phase to obtain a new residual phase threshold, until the ratio of the new residual phase threshold to the residual phase threshold exceeds the preset change threshold, which solves the problem that most target points with similar characteristics to the stable PS points in the slowly deforming area participate in the atmospheric phase estimation and deformation inversion, resulting in atmospheric phase estimation deviation and affecting the deformation inversion accuracy, ensures that the PS points participating in the atmospheric phase estimation have high stability, improves the accuracy of atmospheric estimation, and thus improves the deformation inversion accuracy of the monitoring area.

[0083] In order to understand the ground-based synthetic aperture radar atmospheric compensation method of the present application, FIG2 b provides an application flow chart of the ground-based synthetic aperture radar atmospheric compensation method.

[0084] For the two-dimensional radar complex scattering image sequence of the target monitoring area obtained by ground-based synthetic aperture radar, stable PS points and interferometric phase maps are extracted, and the interferometric phase maps are subjected to two-dimensional spatial unwrapping. The atmospheric model parameters are estimated based on the interferometric phase of the stable PS points. After atmospheric compensation of the PS point interferometric phase, the atmospheric compensated residual phase is obtained, and phase residual statistics are performed. The deformed PS points (including single-frame deformation and short-time accumulated deformation) are eliminated through cyclic threshold judgment until the optimal atmospheric model parameters and optimal atmospheric compensation are obtained.

[0085] Example 3

[0086] Figure 3 is a schematic diagram of the structure of a ground-based synthetic aperture radar atmospheric compensation device provided in Example 3 of the present application. As shown in Figure 3, the device includes: a first PS point set acquisition module 310, an atmospheric compensation residual phase acquisition module 320, a second PS point set acquisition module 330, and an atmospheric compensation operation return execution module 340.

[0087] A first PS point set acquisition module 310 is configured to acquire a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and acquire a first PS point set from the two-dimensional radar complex scattering image sequence;

[0088] an atmospheric compensation residual phase acquisition module 320 configured to perform atmospheric compensation on the PS point interferometric phase by estimating the atmospheric error phase based on a preset atmospheric parameter model and the PS point interferometric phase of the first PS point set, thereby obtaining an atmospheric compensation residual phase;

[0089] a second PS point set acquisition module 330, configured to determine a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and to filter the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set;

[0090] The atmospheric compensation operation returns to the execution module 340, which is configured to return and execute the operation of performing atmospheric compensation on the PS point interference phase by estimating the atmospheric error phase according to the PS point interference phase of the second PS point set to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds a preset change threshold.

[0091] The technical solution of the embodiment of the present application is to obtain a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and obtain a first PS point set from the two-dimensional radar complex scattering image sequence; according to a preset atmospheric parameter model and the PS point interference phase of the first PS point set, the PS point interference phase is atmospherically compensated by estimating the atmospheric error phase to obtain an atmospheric compensated residual phase; a residual phase threshold and a cumulative deformation threshold are determined for the first PS point set based on the atmospheric compensated residual phase, and the first PS point set is screened according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set; according to the PS point interference phase of the second PS point set, an operation of atmospheric compensation for the PS point interference phase by estimating the atmospheric error phase is performed to obtain a new residual phase threshold, until the ratio of the new residual phase threshold to the residual phase threshold exceeds the preset change threshold. This solves the problem that most target points in the slowly deforming area that present similar characteristics to the stable PS points participate in atmospheric phase estimation and deformation inversion, resulting in atmospheric phase estimation deviation and affecting the deformation inversion accuracy. It ensures that the PS points participating in the atmospheric phase estimation have high stability, improves the accuracy of atmospheric estimation, and thereby improves the deformation inversion accuracy of the monitoring area.

[0092] Optionally, the first PS point set acquisition module 310 is configured to:

[0093] The original echo of the target monitoring area is acquired by a ground-based synthetic aperture radar, and the original echo is processed by a radar imaging algorithm to obtain the two-dimensional radar complex scattering image sequence.

[0094] Optionally, the first PS point set acquisition module 310 may include:

[0095] a screening factor determination module configured to determine an average correlation coefficient of each pixel point in the two-dimensional radar complex scattering image sequence, an average relative amplitude of each pixel point in the two-dimensional radar complex scattering image sequence, and an amplitude deviation of a time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence;

[0096] A first candidate PS point set acquisition module is configured to select pixel points whose average correlation coefficient is greater than or equal to a preset average correlation coefficient threshold from the two-dimensional radar complex scattering image sequence as a first candidate PS point set;

[0097] A second candidate PS point set acquisition module is configured to select pixel points whose average relative amplitude is greater than or equal to a preset average relative amplitude threshold from the first candidate PS point set as a second candidate PS point set;

[0098] The first PS point set acquisition submodule is configured to select pixel points whose amplitude deviation is less than or equal to a preset amplitude deviation threshold from the second candidate PS point set as the first PS point set.

[0099] Optionally, the filter factor determination module is set to:

[0100] Acquire, based on the two-dimensional radar complex scattering image sequence, a primary radar complex scattering image, a secondary radar complex scattering image, an amplitude value of each pixel, and a time series of the amplitude of each pixel; wherein the primary radar complex scattering image and the secondary radar complex scattering image are any two adjacent images in the two-dimensional radar complex scattering image sequence;

[0101] determining a correlation coefficient of a target pixel point based on the primary radar complex scattering image and the auxiliary radar complex scattering image, and determining an average correlation coefficient of each target pixel point based on multiple correlation coefficients of target pixels in the two-dimensional radar complex scattering image sequence;

[0102] Determining, based on the amplitude value of each pixel, an amplitude mean of the target pixel in the two-dimensional radar complex scattering image sequence and an average amplitude mean of all target pixels, and determining an average relative amplitude of each target pixel based on the amplitude mean and the average amplitude mean;

[0103] According to the amplitude time series of each pixel point, the standard deviation and mean of the amplitude time series of each pixel point are determined, and according to the standard deviation and mean, the amplitude deviation of the time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence is determined.

[0104] Optionally, the atmospheric compensation residual phase acquisition module 320 is configured as follows:

[0105] extracting an interference phase image sequence according to the two-dimensional radar complex scattering image sequence;

[0106] Acquiring the PS point interference phase of the first PS point set according to the interference phase image sequence;

[0107] performing unwrapping processing on the PS point interference phase to obtain an unwrapped PS point interference phase;

[0108] Solving the atmospheric model parameters of the preset atmospheric parameter model using the least squares method to obtain estimated atmospheric model parameters;

[0109] estimating an atmospheric error phase based on the estimated atmospheric model parameters and the unwrapped PS point interferometric phase;

[0110] The atmospheric error phase is used to perform atmospheric compensation processing on the unwrapped PS point interference phase to obtain the atmospheric compensation residual phase.

[0111] Optionally, the preset atmospheric parameter model is expressed as: Among them, φ atm represents the atmospheric error phase, λ represents the wavelength of the transmission signal of the ground-based synthetic aperture radar, r represents the distance between the ground-based synthetic aperture radar and the target point in the target monitoring area, h represents the elevation difference between the target point and the ground-based synthetic aperture radar in the target monitoring area, β0 represents a constant term, β1 represents a coefficient related to the first power of r, β2 represents a coefficient related to the second power of r, β3 represents a coefficient related to the first power of h, β4 represents a coefficient related to the second power of h, and β5 represents a coefficient related to the first power of r and the first power of h;

[0112] The estimated atmospheric model parameters are obtained by Determine, where φ=[φ1,φ2,…,φ n ] T , φ represents the n×1 dimensional vector formed by the interference phase of n unwrapped PS points, X represents an n×6-dimensional vector consisting of a constant 1 and n PS distances and elevation differences;

[0113] The atmospheric error phase is Sure;

[0114] The atmospheric compensation residual phase is expressed by φsub =φ-φ atm Sure.

[0115] Optionally, the second PS point set acquisition module 330 is configured to:

[0116] Determine, based on the atmospheric compensation residual phase, the mean and standard deviation of the deformation value of the PS point corresponding to the atmospheric compensation residual phase, and determine a single-frame deformation image after the atmospheric compensation is performed on the interference phase of the PS point;

[0117] Determining the residual phase threshold according to the mean, standard deviation and preset single-frame deformation threshold coefficient of the PS point deformation values;

[0118] constructing a short-time deformation image sequence according to the single-frame deformation image, summing the short-time deformation image sequence to obtain a short-time cumulative image, and calculating the mean and variance of corresponding values ​​of the PS point in the short-time cumulative image;

[0119] The cumulative deformation threshold is determined according to the mean, variance and preset cumulative deformation threshold coefficient of the corresponding values ​​of the PS point in the short-time cumulative image.

[0120] The ground-based synthetic aperture radar atmospheric compensation device provided in the embodiment of the present application can execute the ground-based synthetic aperture radar atmospheric compensation method provided in any embodiment of the present application, and has the functional modules and effects corresponding to the execution method.

[0121] Example 4

[0122] 4 shows a schematic diagram of an electronic device 400 that can be used to implement an embodiment of the present application. The components, their connections and relationships, and their functions shown herein are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0123] As shown in Figure 4, the electronic device 400 includes at least one processor 401, and a memory connected to the at least one processor 401, such as a read-only memory (ROM) 402, a random access memory (RAM) 403, etc., wherein the memory stores a computer program that can be executed by the at least one processor 401, and the processor 401 can perform a variety of appropriate actions and processes according to the computer program stored in the ROM 402 or the computer program loaded from the storage unit 408 into the RAM 403. In the RAM 403, a variety of programs and data required for the operation of the electronic device 400 can also be stored. The processor 401, ROM 402 and RAM 403 are connected to each other via a bus 404. An input / output (I / O) interface 405 is also connected to the bus 404.

[0124] Multiple components in the electronic device 400 are connected to the I / O interface 405, including an input unit 406, such as a keyboard, a mouse, etc.; an output unit 407, such as various types of displays, speakers, etc.; a storage unit 408, such as a magnetic disk, an optical disk, etc.; and a communication unit 409, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 409 allows the electronic device 400 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0125] Processor 401 can be a variety of general-purpose and / or specialized processing components with processing and computing capabilities. Some examples of processor 401 include a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. Processor 401 performs the various methods and processes described above, such as the ground-based synthetic aperture radar atmospheric compensation method.

[0126] In some embodiments, the ground-based synthetic aperture radar atmospheric compensation method can be implemented as a computer program tangibly embodied in a computer-readable storage medium, such as storage unit 408. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 400 via ROM 402 and / or communication unit 409. When the computer program is loaded into RAM 403 and executed by processor 401, one or more steps of the ground-based synthetic aperture radar atmospheric compensation method described above can be performed. Alternatively, in other embodiments, processor 401 can be configured to execute the ground-based synthetic aperture radar atmospheric compensation method in any other appropriate manner (e.g., via firmware).

[0127] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard parts (ASSPs), system on chips (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0128] Computer programs for implementing the methods of the present application may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0129] In the context of the present application, computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage medium can include electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage medium can be a machine-readable signal medium. Machine-readable storage medium includes an electrical connection based on one or more lines, a portable computer disk, a hard disk, RAM, ROM, erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device or any suitable combination of the foregoing. Storage medium can be a non-transitory storage medium.

[0130] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a cathode ray tube (CRT) or a liquid crystal display (LCD) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0131] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0132] A computing system may include a client and a server. The client and server are generally remote from each other and typically interact via a communication network. The client-server relationship arises through computer programs running on the respective computers and establishing a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, a host product within a cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosts and virtual private server (VPS) services.

[0133] The various forms of processes shown above can be used to reorder, add, or delete steps. For example, the multiple steps described in this application can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of this application can be achieved. This document is not limited here.

[0134] The above embodiments do not limit the scope of protection of this application. Various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors.

Claims

1. A method for atmospheric compensation of a ground-based synthetic aperture radar, comprising: Acquire a two-dimensional radar complex scattering image sequence of the target monitoring area through a ground-based synthetic aperture radar, and acquire a first PS point set from the two-dimensional radar complex scattering image sequence; According to a preset atmospheric parameter model and the PS point interference phase of the first PS point set, atmospheric compensation is performed on the PS point interference phase by estimating the atmospheric error phase to obtain an atmospheric compensation residual phase; Determining a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and screening the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set; According to the PS point interference phase of the second PS point set, the operation of performing atmospheric compensation on the PS point interference phase by estimating the atmospheric error phase is returned to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds a preset change threshold.

2. The method according to claim 1, wherein: The method of acquiring a two-dimensional radar complex scattering image sequence of a target monitoring area by using a ground-based synthetic aperture radar comprises: The original echo of the target monitoring area is acquired by the ground-based synthetic aperture radar, and the original echo is processed by a radar imaging algorithm to obtain the two-dimensional radar complex scattering image sequence.

3. The method according to claim 1, wherein: The step of acquiring a first PS point set from the two-dimensional radar complex scattering image sequence comprises: Determine an average correlation coefficient of each pixel point in the two-dimensional radar complex scattering image sequence, an average relative amplitude of each pixel point in the two-dimensional radar complex scattering image sequence, and an amplitude deviation of a time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence; Selecting pixel points whose average correlation coefficient is greater than or equal to a preset average correlation coefficient threshold from the two-dimensional radar complex scattering image sequence as a first candidate PS point set; Select pixel points whose average relative amplitude is greater than or equal to a preset average relative amplitude threshold from the first candidate PS point set as a second candidate PS point set; Pixel points whose amplitude deviation is less than or equal to a preset amplitude deviation threshold are selected from the second candidate PS point set as the first PS point set.

4. The method according to claim 3, wherein: The step of determining an average correlation coefficient of each pixel point in the two-dimensional radar complex scattering image sequence, an average relative amplitude of each pixel point in the two-dimensional radar complex scattering image sequence, and an amplitude deviation of a time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence comprises: According to the two-dimensional radar complex scattering image sequence, a main radar complex scattering image, an auxiliary radar complex scattering image, an amplitude value of each pixel point and an amplitude time series of each pixel point are obtained, wherein the main The radar complex scattering image and the auxiliary radar complex scattering image are any two adjacent images in the two-dimensional radar complex scattering image sequence; Determine a correlation coefficient of a target pixel point according to the primary radar complex scattering image and the auxiliary radar complex scattering image, and determine an average correlation coefficient of each target pixel point according to multiple correlation coefficients of the target pixel points in the two-dimensional radar complex scattering image sequence; Determine, according to the amplitude value of each pixel, the amplitude mean of the target pixel in the two-dimensional radar complex scattering image sequence and the average amplitude mean of all target pixel points, and determine the average relative amplitude of each target pixel point according to the amplitude mean and the average amplitude mean; According to the amplitude time series of each pixel point, the standard deviation and the mean of the amplitude time series of each pixel point are determined, and according to the standard deviation and the mean, the amplitude deviation of the time-series complex scattering image corresponding to the two-dimensional radar complex scattering image sequence is determined.

5. The method according to claim 1, wherein: The method of performing atmospheric compensation on the PS point interference phase by estimating the atmospheric error phase according to the preset atmospheric parameter model and the PS point interference phase of the first PS point set to obtain the atmospheric compensation residual phase comprises: Extracting an interference phase image sequence according to the two-dimensional radar complex scattering image sequence; According to the interference phase image sequence, obtaining the PS point interference phase of the first PS point set; Performing unwrapping processing on the PS point interference phase to obtain an unwrapped PS point interference phase; Solving the atmospheric model parameters of the preset atmospheric parameter model using the least squares method to obtain estimated atmospheric model parameters; estimating the atmospheric error phase according to the estimated atmospheric model parameters and the unwrapped PS point interference phase; The atmospheric error phase is used to perform atmospheric compensation processing on the unwrapped PS point interference phase to obtain the atmospheric compensation residual phase.

6. The method according to claim 5, wherein: The preset atmospheric parameter model is expressed as: Among them, φ atm represents the atmospheric error phase, λ represents the wavelength of the transmission signal of the ground-based synthetic aperture radar, r represents the distance between the ground-based synthetic aperture radar and the target point in the target monitoring area, h represents the elevation difference between the target point and the ground-based synthetic aperture radar in the target monitoring area, β0 represents a constant term, β1 represents a coefficient related to the first power of r, β2 represents a coefficient related to the second power of r, β3 represents a coefficient related to the first power of h, β4 represents a coefficient related to the second power of h, and β5 represents a coefficient related to the first power of r and the first power of h; The estimated atmospheric model parameters are obtained by Determine, where φ=[φ1,φ2,…,φ n ] T , φ represents the n×1 dimensional vector formed by the interference phase of n unwrapped PS points, X represents a n×6-dimensional vector consisting of a constant 1 and n PS distances and elevation differences; The atmospheric error phase is Sure; The atmospheric compensation residual phase is expressed by φ sub =φ-φ atm Sure.

7. The method according to claim 1, wherein: The determining a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase includes: According to the atmospheric compensation residual phase, determine the mean and standard deviation of the deformation value of the PS point corresponding to the atmospheric compensation residual phase, and determine a single-frame deformation image after the atmospheric compensation is performed on the interference phase of the PS point; Determining the residual phase threshold according to the mean, standard deviation and preset single-frame deformation threshold coefficient of the PS point deformation value; Constructing a short-time deformation image sequence according to the single-frame deformation image, summing the short-time deformation image sequence to obtain a short-time accumulation image, and calculating the mean and variance of the corresponding values ​​of the PS point in the short-time accumulation image; The cumulative deformation threshold is determined according to the mean, variance and preset cumulative deformation threshold coefficient of the corresponding values ​​of the PS point in the short-time cumulative image.

8. A ground-based synthetic aperture radar atmosphere compensation device, comprising: A first PS point set acquisition module is configured to acquire a two-dimensional radar complex scattering image sequence of a target monitoring area through a ground-based synthetic aperture radar, and acquire a first PS point set from the two-dimensional radar complex scattering image sequence; an atmospheric compensation residual phase acquisition module, configured to perform atmospheric compensation on the PS point interference phase by estimating the atmospheric error phase according to a preset atmospheric parameter model and the PS point interference phase of the first PS point set, so as to obtain an atmospheric compensation residual phase; a second PS point set acquisition module, configured to determine a residual phase threshold and a cumulative deformation threshold for the first PS point set according to the atmospheric compensation residual phase, and to screen the first PS point set according to the residual phase threshold and the cumulative deformation threshold to obtain a second PS point set; The atmospheric compensation operation returns to the execution module, which is set to be based on the PS point interference phase of the second PS point set. The bit return executes the operation of performing atmospheric compensation on the PS point interference phase through the estimated atmospheric error phase to obtain a new residual phase threshold until the ratio of the new residual phase threshold to the residual phase threshold exceeds a preset change threshold.

9. An electronic device, comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can perform the ground-based synthetic aperture radar atmosphere compensation method according to any one of claims 1 to 7.

10. A computer-readable storage medium, wherein: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the ground-based synthetic aperture radar atmosphere compensation method according to any one of claims 1 to 7 when executed.

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