CN118584488B - A method, device, storage medium and electronic device for correcting atmospheric delay error - Google Patents
A method, device, storage medium and electronic device for correcting atmospheric delay error Download PDFInfo
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Abstract
本申请涉及地形观测技术领域，具体提供了一种大气延迟误差修正的方法、装置、存储介质及电子设备，该方法可以包括：获取待修正合成孔径雷达InSAR干涉图中每个窗口的窗口参数，其中，所述窗口参数包括：地形相关系数、空间自相关系数和相位梯度；通过将所述窗口参数与预设条件进行对比，确定所述待修正InSAR干涉图中每个窗口的尺寸，得到窗口修正后干涉图；通过相位拟合公式对所述窗口修正后干涉图中的初始干涉相位进行修正，得到目标InSAR干涉图，其中，所述相位拟合公式与观测点的水平位置参数和高程参数相关。本申请的一些实施例可以提升InSAR干涉图的精度。
The present application relates to the field of terrain observation technology, and specifically provides a method, device, storage medium and electronic device for correcting atmospheric delay errors. The method may include: obtaining window parameters of each window in a synthetic aperture radar InSAR interferogram to be corrected, wherein the window parameters include: terrain correlation coefficient, spatial autocorrelation coefficient and phase gradient; determining the size of each window in the InSAR interferogram to be corrected by comparing the window parameters with preset conditions, and obtaining a window-corrected interferogram; correcting the initial interference phase in the window-corrected interferogram by a phase fitting formula, and obtaining a target InSAR interferogram, wherein the phase fitting formula is related to the horizontal position parameter and elevation parameter of the observation point. Some embodiments of the present application can improve the accuracy of the InSAR interferogram.
Description
Technical Field
The application relates to the technical field of topography observation, in particular to a method and a device for correcting atmospheric delay errors, a storage medium and electronic equipment.
Background
With the rapid development of interferometric synthetic aperture radar (InSAR, SYNTHETIC APERTURE RADAR INTERFEROMETRY) technology, it is an important observation means for detecting high spatial resolution surface deformation. The technology is successfully applied to the field of measuring the surface deformation monitoring scene related to hydrology, volcano, structural movement and the like. However, when InSAR is used to measure small-amplitude and long-wavelength structural deformation (such as inter-seismic deformation, diving band slow slip event, creep and the like) signals, the signals are seriously affected by atmospheric disturbance, so that the accuracy of subsequent surface deformation monitoring is affected.
Currently, in order to improve the accuracy of the InSAR technique in a surface deformation monitoring scenario, an empirical method is generally adopted in the face of the atmospheric delays existing in the InSAR interferogram. The empirical method is to determine empirical fitting parameters for atmospheric disturbance characteristics of different research areas to attenuate long wavelength atmospheric errors related to terrain on an interferogram. However, the experience method has strong subjective consciousness, and although errors can be corrected to a certain extent, the accuracy of the interferograms is still not guaranteed.
Therefore, how to provide a method for correcting the atmospheric delay error with higher accuracy becomes a technical problem to be solved.
Disclosure of Invention
It is an object of some embodiments of the present application to provide a method of atmospheric delay error correction, an apparatus, a storage medium and an electronic device, according to the technical scheme provided by the embodiment of the application, the accuracy of the correction of the atmospheric delay error can be improved, and the accuracy of topography observation is further improved.
In a first aspect, some embodiments of the present application provide a method of atmospheric delay error correction, comprising: acquiring window parameters of each window in an InSAR interferogram to be corrected, wherein the window parameters comprise: terrain correlation coefficients, spatial autocorrelation coefficients, and phase gradients; comparing the window parameters with preset conditions, and determining the size of each window in the InSAR interferogram to be corrected to obtain a window corrected interferogram; and correcting the initial interference phase in the interference pattern after window correction through a phase fitting formula to obtain a target InSAR interference pattern, wherein the phase fitting formula is related to the horizontal position parameter and the elevation parameter of the observation point.
According to some embodiments of the application, window parameters in the InSAR interferogram to be corrected are compared with preset conditions, and window sizes are corrected to obtain a window corrected interferogram; and then correcting the initial interference phase in the interference pattern after window correction through a phase fitting formula to obtain a target InSAR interference pattern. According to the embodiment of the application, the interference phase is corrected after the window size is corrected, so that the accuracy and the effectiveness of the correction of the atmospheric delay error can be improved, and the accuracy of topography observation is further improved.
In some embodiments, the obtaining the window parameter of each window in the synthetic aperture radar InSAR interferogram to be corrected includes: fitting the original InSAR interferogram to obtain the InSAR interferogram to be corrected; sliding the set initial window on the InSAR interferogram to be corrected according to the sliding step length to obtain a sliding window in an adjacent state and the initial window; and respectively calculating the window parameters corresponding to the sliding window and the initial window.
According to the method and the device, the corresponding window parameters can be conveniently obtained by processing and sliding the original InSAR interferogram, and an effective data basis is provided for subsequent correction.
In some embodiments, the determining the size of each window in the InSAR interferogram to be corrected by comparing the window parameter with a preset condition includes: if the window parameters meet the preset conditions, combining the sliding window with the initial window to obtain a combined window size, wherein the combined window size is one window in the InSAR interferogram to be corrected; and if the window parameters are confirmed not to meet the preset conditions, taking the sliding window as one window in the InSAR interferogram to be corrected.
According to some embodiments of the application, the window parameters are compared with the preset conditions, and the adjacent windows are processed, so that the accuracy of window division can be improved, and data with higher accuracy can be provided for subsequent correction.
In some embodiments, the confirming that the window parameter meets the preset condition includes: confirming that the topographic correlation coefficients corresponding to the sliding window and the initial window are larger than a first threshold value, the phase value signs of the spatial autocorrelation coefficients corresponding to the sliding window and the initial window are the same, and the difference value of the phase gradients corresponding to the sliding window and the initial window is smaller than a second threshold value.
According to the method and the device, parameters in the window parameters are compared with corresponding conditions, and the fact that preset conditions are met is confirmed under the condition that the parameters are met, so that the window size can be accurately divided.
In some embodiments, the correcting the initial interference phase in the interference pattern after the window correction by the phase fitting formula to obtain the target InSAR interference pattern includes: calculating a differential interference phase observation value of an observation point in each window in the interference diagram after window correction through the phase fitting formula; and correcting the initial interference phase according to the differential interference phase observation value to obtain the target InSAR interferogram.
According to some embodiments of the application, the differential interference phase observation value of the observation point is determined through a phase fitting formula, then the initial interference phase is corrected, a target InSAR interferogram is obtained, and the accurate correction of the atmospheric delay error in the interferogram can be realized.
In some embodiments, the phase fitting formula is obtained by determining parameters to be estimated in the phase fitting formula by a least square method based on observed data; wherein the observation data includes: the observation point coordinates and the phase difference value, the observation point coordinates include: a horizontal position parameter and an elevation parameter.
In a second aspect, some embodiments of the present application provide an apparatus for atmospheric delay error correction, comprising: the system comprises a window parameter acquisition module, a window parameter correction module and a window parameter correction module, wherein the window parameter acquisition module is used for acquiring the window parameter of each window in an InSAR interferogram to be corrected, and the window parameter comprises: terrain correlation coefficients, spatial autocorrelation coefficients, and phase gradients; the window size correction module is used for determining the size of each window in the InSAR interferogram to be corrected by comparing the window parameters with preset conditions to obtain a window corrected interferogram; the phase correction module is used for correcting the initial interference phase in the interference pattern after window correction through a phase fitting formula to obtain a target InSAR interference pattern, wherein the phase fitting formula is related to the horizontal position parameter and the elevation parameter of the observation point.
In a third aspect, some embodiments of the application provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs a method according to any of the embodiments of the first aspect.
In a fourth aspect, some embodiments of the application provide an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor is operable to implement a method according to any of the embodiments of the first aspect when executing the program.
In a fifth aspect, some embodiments of the application provide a computer program product comprising a computer program, wherein the computer program, when executed by a processor, is adapted to carry out the method according to any of the embodiments of the first aspect.
Drawings
In order to more clearly illustrate the technical solutions of some embodiments of the present application, the drawings that are required to be used in some embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be construed as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort to those of ordinary skill in the art.
FIG. 1 is a flow chart of a method for atmospheric delay error correction according to some embodiments of the present application;
FIG. 2 is a schematic view of window sliding provided by some embodiments of the present application;
FIG. 3 is a second flowchart of a method for atmospheric delay error correction according to some embodiments of the present application;
FIG. 4 is a diagram illustrating a comparison of GPS deformation velocity fields according to some embodiments of the present application;
FIG. 5 is a block diagram of an apparatus for atmospheric delay error correction according to some embodiments of the present application;
fig. 6 is a schematic diagram of an electronic device according to some embodiments of the present application.
Detailed Description
The technical solutions of some embodiments of the present application will be described below with reference to the drawings in some embodiments of the present application.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.
In the related art, the InSAR atmospheric delay is caused by the change of the interference phase due to the space-time change of the refractive index of air, and has complex spatial characteristics along with the change of pressure, temperature and water vapor content. The phase delay is the combined effect of turbulent and stratified turbulent mixing in the atmosphere. InSAR atmospheric delays include ionospheric delays and tropospheric delays. Ionosphere typically affects radar signals on a large scale, with less impact on either X or C band radar signals. The atmospheric delay referred to in the present application refers to tropospheric delay.
Specifically, the atmospheric delays in the InSAR interferograms are caused by changes in the atmospheric refractive index in the two SAR acquisitions. It mainly comprises three parts: (1) terrain-related atmospheric disturbances; (2) a spatially autocorrelation disturbance; (3) spatially anisotropic atmospheric turbulence. Atmospheric phase changes or delays introduce significant errors of several cm in the InSAR observations and often cover the deformation signal of interest. In particular, for deformation monitoring of constructional movements in the order of mm, atmospheric error correction is particularly important. Therefore, the method for improving the monitoring capability of InSAR data on the surface deformation and effectively weakening the InSAR atmospheric delay effect has very important significance.
Existing correction methods for InSAR atmospheric delay can be divided into two categories, namely prediction methods and empirical methods. The prediction method is a method for correcting based on external atmospheric delay data. For example: and using the atmospheric delay disturbance data based on GNSS and remote sensing satellites and the tropospheric delay estimated by the model, and a GACOS (Generic Atmospheric Correction Online Service) atmospheric correction model obtained by integrating GPS, ECMWF and terrain data. The above-described prediction method has been successfully applied to attenuate terrain-dependent long-wavelength atmospheric errors on interferograms. The empirical method is a method of performing atmospheric phase estimation and correction using the InSAR data itself. The key to atmospheric delay correction by the empirical method is to determine the empirical fitting parameters (linear or exponential) for the atmospheric disturbance characteristics of different study areas. Empirical methods typically employ linear estimates of the delayed terrain-related components based on the terrain characteristics of the area of investigation. Turbulence and coherent short-scale components cannot be explained based on the assumption of a single relationship between the entire interferogram. In order to take into account turbulence and atmospheric disturbances of short spatial dimensions, the prior art proposes methods for performing atmospheric delay correction at different spatial dimensions. For example, it is proposed in the prior art to estimate terrain-related atmospheric disturbances using gaussian filters of different fixed widths. But this approach ignores the spatial variability of the tropospheric signals. In addition, it has been proposed in the prior art to divide the investigation region into a plurality of rectangular windows over which the relationship between local phase and terrain is estimated, taking into account the spatially correlated power law model at the same time. The window is then interpolated to all data points by weighting it using the distance from the data point and the estimated window uncertainty. The power law reference altitude h0 and the power law coefficient α are constants estimated from balloon sounding data or weather model data. External atmosphere model correction data is therefore required as auxiliary data.
Moreover, the key to the empirical approach is the determination of the filter window, the filter window length should reflect the degree of correlation. The window length affects the results obtained using the time-space filtering method and it may vary spatially. The above empirical method estimates the atmospheric delay method, typically by dividing the correction window only according to the terrain or subjectively dividing the filtering window of the investigation region, and further by using a linear or exponential function to attenuate the atmospheric disturbances associated with the terrain. The specific need divides the atmospheric delay correction windows of different spatial scales according to the specific spatial characteristics of the residual phases in the interferograms.
However, methods of correction based on external atmospheric delay data are generally limited by spatial and temporal resolution and accuracy of the assistance data. The external model may produce a situation of correction underestimation or overestimation, subject to the constraint of lower spatial-temporal resolution and accuracy, in particular, the InSAR interferogram with large terrain variation and strong atmospheric disturbance. The above-mentioned empirical method is effective only for correcting the atmospheric delay error associated with the terrain only according to the division of the terrain to the filtering window, but does not consider the correlation between other data and the terrain and the characteristics of the spatial autocorrelation and the spatial anisotropy of the atmospheric delay error, etc., so that the accuracy of the correction of the atmospheric delay error is still to be studied.
As known from the above related art, the accuracy of the correction of the atmospheric delay error in the prior art needs to be improved.
In view of this, some embodiments of the present application provide a method for correcting an atmospheric delay error, which may calculate a plurality of different types of window parameters in an InSAR interferogram to be corrected, and then correct a window size by using the window parameters and a preset condition to obtain a window corrected interferogram; and finally, correcting the initial interference phase in the interference pattern after window correction by a phase fitting formula to obtain a corrected target InSAR interference pattern. According to the method and the device, the correlation between the phase and the terrain and the correlation characteristics such as the spatial autocorrelation and the spatial anisotropy of the atmospheric delay error are considered, so that the correction accuracy is improved, and the accuracy of monitoring the surface deformation is further improved.
The implementation of the atmospheric delay error correction provided by some embodiments of the present application is described below by way of example with reference to fig. 1.
Referring to fig. 1, fig. 1 is a flowchart of a method for correcting an atmospheric delay error according to some embodiments of the present application, where the method for correcting an atmospheric delay error may include:
S110, acquiring window parameters of each window in the InSAR interferogram to be corrected, wherein the window parameters comprise: terrain correlation coefficients, spatial autocorrelation coefficients, and phase gradients.
For example, in some embodiments of the present application, the relationship between the characteristic parameters is comprehensively considered by calculating the topographic correlation coefficient, the spatial autocorrelation coefficient and the phase gradient of each window in the interferogram, so as to improve the accuracy of the correction of the atmospheric delay error. The spatial autocorrelation coefficients are mainly used for describing the average association degree of all spatial units with the surrounding areas in the whole area, and can be obtained through a common calculation formula.
In some embodiments of the present application, S110 may include: fitting the original InSAR interferogram to obtain the InSAR interferogram to be corrected; sliding the set initial window on the InSAR interferogram to be corrected according to the sliding step length to obtain a sliding window in an adjacent state and the initial window; and respectively calculating the window parameters corresponding to the sliding window and the initial window.
For example, in some embodiments of the application, a differential interference phase map (as a specific example of the original InSAR interferogram) is obtained using the D-InSAR technique based on satellite SAR observations. A second order linear fit (as a specific example of a fitting process) is then used to eliminate the phase ramp caused by the track error in the differential interference phase map. And finally, setting the sliding step length and the size of the initial window, sliding the initial window according to the sliding step length on the InSAR interferogram to be corrected, and calculating and analyzing the window parameters of the generated adjacent windows. For example, as shown in fig. 2 (fig. 2 has been a state of sliding d0 to the right). The initial window is a region composed of black thick lines, the size of the initial window is a0×a0, and the sliding step size is d0. When the initial window slides to the right by d0, a sliding window of a0×d0 (i.e., the area surrounded by the dotted line in fig. 2) and an initial window of a0×a0 (i.e., the area surrounded by the black thick line in fig. 2) can be obtained, where the two windows are adjacent windows. And respectively calculating the two windows through the InSAR interferograms to be corrected to obtain window parameters corresponding to each window. It will be appreciated that d0 and the initial window size may be set according to the actual topography, and embodiments of the present application are not specifically limited herein.
S120, comparing the window parameters with preset conditions, and determining the size of each window in the InSAR interferogram to be corrected to obtain a window corrected interferogram.
For example, in some embodiments of the present application, the topographic correlation coefficient, the spatial autocorrelation coefficient, and the phase gradient are compared with corresponding preset conditions respectively to determine a size of each window to be corrected, and after the processing of the entire region of the InSAR interferogram to be corrected is completed, a window corrected interferogram is obtained. The preset conditions may include a plurality of conditions related to window parameters, which are not particularly limited herein.
To facilitate the elucidation of the window size correction process, an exemplary explanation is provided below in connection with two adjacent windows of fig. 2.
In some embodiments of the present application, S120 may include: and if the window parameters meet the preset conditions, merging the sliding window with the initial window to obtain a merged window size, wherein the merged window size is one window in the InSAR interferogram to be corrected. Wherein, the confirming that the window parameter meets the preset condition comprises: confirming that the topographic correlation coefficients corresponding to the sliding window and the initial window are larger than a first threshold value, the phase value signs of the spatial autocorrelation coefficients corresponding to the sliding window and the initial window are the same, and the difference value of the phase gradients corresponding to the sliding window and the initial window is smaller than a second threshold value.
For example, in some embodiments of the present application, the preset conditions include a total of 3 conditions, namely: the topographic correlation coefficients of adjacent windows are all larger than a first threshold r3; the phase values of adjacent windows are the same number; the difference in phase values of adjacent windows is less than a second threshold r1. When the window parameters of the adjacent sliding window and the initial window in fig. 2 satisfy the above 3 conditions, a correction is required, and the specific correction method is as follows: combining the two to obtain a window with the combined window size of (a0+d0) x a 0. It should be understood that the values of r1 and r3 may be set according to practical applications, and embodiments of the present application are not limited herein specifically. It should be noted that, the content of the preset condition is an embodiment of the present application, and in actual situations, the preset condition may be adaptively adjusted based on the acquired window parameter, which is not limited to this embodiment of the present application.
After the window size after combination is obtained, the initial window slides rightwards by d0 again, and the window size of the left side adjacent to the initial window is 2d0 multiplied by a0; and comparing the window with the initial window again in the mode, if the window is combined, continuing to move to the right d0 in the mode for analysis, and the like.
In other embodiments of the present application, S120 may include: and if the window parameters are confirmed not to meet the preset conditions, taking the sliding window as one window in the InSAR interferogram to be corrected.
For example, in some embodiments of the present application, if there are window parameters of the adjacent sliding window and the initial window in fig. 2 that do not satisfy one of the above 3 conditions, no correction is required, that is, no window merging is required, and the sliding window is used as an independent window.
After the first resizing is completed, the initial window is slid to the right again by d0, the newly generated sliding window of a0×d0 is compared with the initial window again in the manner described above, whether to combine or form a new window alone is determined, and so on.
And after the whole area of the InSAR interferogram to be corrected is searched, determining a multi-scale window corrected interferogram with the window size corrected.
S130, correcting an initial interference phase in the interference pattern after window correction through a phase fitting formula to obtain a target InSAR interference pattern, wherein the phase fitting formula is related to a horizontal position parameter and an elevation parameter of an observation point.
For example, in some embodiments of the present application, the initial interference phase of the observation point in the map is corrected by the phase fitting formula newly proposed by the present application, so as to obtain a corrected target InSAR interferogram. The phase fitting formula in the application considers the overall condition of the horizontal position parameter change and the elevation parameter change at the same time during fitting, so that the accuracy of the atmospheric delay error correction can be improved to a certain extent, and the method has better universality.
In some embodiments of the present application, the phase fitting formula is obtained by determining parameters to be estimated in the phase fitting formula by using a least square method based on observed data; wherein the observation data includes: the observation point coordinates and the phase difference value, the observation point coordinates include: a horizontal position parameter and an elevation parameter.
For example, in some embodiments of the application, the phase fitting formula is:
Wherein a, b, C, C 0, C and alpha are parameters to be estimated, and x, y and h are horizontal position parameters and elevation parameters of the observation points respectively. For differential interferometric phase observations (i.e., error values resulting from terrain and position dependent atmospheric delay disturbances).
The parameters to be estimated are obtained by fitting phases through a least square method through known observation data.
In some embodiments of the present application, S130 may include: calculating a differential interference phase observation value of an observation point in each window in the interference diagram after window correction through the phase fitting formula; and correcting the initial interference phase according to the differential interference phase observation value to obtain the target InSAR interferogram.
For example, in some embodiments of the present application, the coordinates (x, y, h) of the observation point of each window are input into the phase fitting formula, so that the corresponding observation point can be obtained. The initial interference phase is calculatedAs a corrected phase value. And after each window observation point is corrected, obtaining a corrected target InSAR interferogram.
Finally, based on the target InSAR interferogram, the deformation amount and deformation rate are estimated by adopting a time sequence InSAR technology (e.g. SBAS algorithm).
The specific process of atmospheric delay error correction provided by some embodiments of the present application is described below by way of example with reference to fig. 3.
Referring to fig. 3, fig. 3 is a flowchart illustrating a method for correcting an atmospheric delay error according to some embodiments of the present application.
The above-described process is exemplarily set forth below.
S310, acquiring original InSAR observation data.
S320, obtaining an original InSAR interferogram by adopting a D-InSAR technology.
S330, adopting second-order linear fitting to the original InSAR interferogram to obtain the InSAR interferogram to be corrected.
And S340, sliding the set initial window on the InSAR interferogram to be corrected according to the sliding step length to obtain an adjacent window in an adjacent state.
S350, window parameters corresponding to the sliding window and the initial window are calculated respectively.
S360, comparing the window parameters with preset conditions, and confirming whether the window size is corrected, if so, executing S361, otherwise, returning to S370.
S361, merging the adjacent windows to obtain a merged window, and executing S370.
S370, judging whether the whole area search is completed, if yes, executing S380, otherwise returning to S340.
After the whole area search is completed, the interference pattern after window correction can be obtained.
S380, calculating differential interference phase observation values of observation points in each window in the interference diagram after window correction through a phase fitting formula.
S390, correcting the initial interference phase according to the differential interference phase observation value to obtain a target InSAR interferogram.
S391, estimating deformation quantity and deformation rate by adopting a time sequence InSAR technology based on the target InSAR interferogram.
It should be noted that, the specific implementation process of S310 to S391 may refer to the method embodiments provided above, and detailed descriptions are omitted here appropriately to avoid repetition.
According to the embodiments of the application, the prior atmospheric or water vapor model data is not needed as the prior condition, and the correction area is not needed to be divided according to experience, so that the correction window can be automatically divided according to the spatial characteristics of terrain, interference phase and atmospheric delay. And the atmospheric delay correction of multiple spatial scales can be realized, and the spatial variation characteristics of the atmospheric delay disturbance are considered, so that the accuracy is higher and the universality is higher.
In order to verify the feasibility of the method for correcting the atmospheric delay error, the method provided by the application is compared with the existing atmospheric delay correction model.
Specifically, the lifting rail observation data of Sentinel-1A in a certain sea area are selected as an example, and the 3 atmosphere correction methods including the invention are subjected to comparison test.
The dimensional change is not obvious at tens of km due to the structural deformation of the investigation region. The sliding window size is preferably tens of km, the optimal initial sliding window size is determined through multiple experiments, a 24-32km sliding window is arranged in the research area, the spatial scale of atmospheric delay disturbance is considered to be several kilometers to tens of kilometers, and the small spatial scale is insensitive to troposphere signals, so that the sliding step length is set to be about 8km. Because the test aims at the differential interference phase of the small space-time base line, the time base line is set to be less than 180 day, the threshold value of the phase is set to be 2rad and is about 4.5mm, and the structural deformation of the research area is less than 18mm/yr, the setting of 2rad is reasonable, and the structural signal is ensured not to be weakened.
Method 1 is a method proposed by the invention, method 2 is an exponential model method with a single spatial scale, and method 3 is a GACOS atmospheric delay correction model.
And respectively carrying out precision analysis on the resolving result from three aspects of residual phase of the interferogram, inSAR deformation speed field precision analysis and deformation time sequence analysis. Firstly, 105 pairs of interference image calculation results formed by the selected 29-scene Sentinel-1A track lifting (T55) image show that the method can effectively weaken the atmosphere delay disturbance of the topographic correlation and the space autocorrelation. The above three methods are adopted to correct the atmospheric delay of the unwrapped interference phase. The interference phase map was corrected by generating 105 for the 29 th view image of the Sentinel-1A track, table 1 is a statistical case of standard deviation of residual phases of 105 interference phase maps of the T55 track and 113 interference phase maps of the T62 track, and the average value of the interference phases before and after the atmospheric delay correction was obtained by using 3 methods.
TABLE 1
Method 2 and method 3 are phase averages corrected using a single scale index model and GACOS atmospheric delay correction model, respectively. As can be seen from the phase average value result, the phase of the fitting result by adopting the method is minimum and is better than that of the result without atmospheric delay correction. The method reduces the phase average value calculated by the method 2 by 0.2-0.3rad. And the vertical layering phases of medium and small spatial scales related to the terrain still exist in the interference phases of the method 2 and the method 3. There is also a spatially auto-correlated atmospheric delay phase. After the atmospheric delay is weakened by adopting the method, the average value of the track lifting interference phase residual error is reduced from 2.1rad to 1.66rad, and the attenuation is about 21%; the average value of the derailment interference phase residuals is from 1.79rad less to 1.04rad, attenuated by about 41%. However, the phase residual error result after correction in the method 3 is smaller than the uncorrected result and is close to the phase residual error of the atmospheric delay related to the terrain with only large spatial scale, which means that the method 3 can correct most of the long wave phase related to the terrain, but the atmospheric delay disturbance correction effect with small spatial scale is not good.
In order to verify the effectiveness of different atmosphere delay correction methods, the three methods are adopted to perform atmosphere delay correction on the InSAR interference phase in experiments, and an InSAR deformation speed field is obtained. By comparing the GPS deformation speed field results, the effectiveness of three types of atmospheric delay correction methods can be compared. And projecting the three-dimensional deformation speed field of the GPS to the InSAR view line, and comparing the deformation speed field with the InSAR deformation speed field. FIG. 4 shows the RMS of the residual error of the InSAR deformation speed field corrected by the three methods, compared to the GPS deformation speed field (InSAR deformation speed field obtained by different atmospheric delay correction methods) (a is an ascending rail and b is a descending rail). From the calculation results, it can be seen that the RMS of the residual error (i.e., the 3D RMS in fig. 4) of the method proposed by the present invention is minimum, which indicates that the correction effect of the method is optimal.
Referring to fig. 5, fig. 5 is a block diagram illustrating an apparatus for correcting an atmospheric delay error according to some embodiments of the present application. It should be understood that the apparatus for correcting an atmospheric delay error corresponds to the above method embodiment, and can perform the steps related to the above method embodiment, and specific functions of the apparatus for correcting an atmospheric delay error may be referred to the above description, and detailed descriptions thereof are omitted herein as appropriate to avoid redundancy.
The apparatus for atmospheric delay error correction of fig. 5 includes at least one software functional module capable of being stored in a memory in the form of software or firmware or being solidified in the apparatus for atmospheric delay error correction, the apparatus for atmospheric delay error correction comprising: a window parameter obtaining module 410, configured to obtain a window parameter of each window in the synthetic aperture radar InSAR interferogram to be corrected, where the window parameter includes: terrain correlation coefficients, spatial autocorrelation coefficients, and phase gradients; the window size correction module 420 is configured to determine a size of each window in the InSAR interferogram to be corrected by comparing the window parameter with a preset condition, so as to obtain a window corrected interferogram; the phase correction module 430 is configured to correct an initial interference phase in the interference pattern after the window correction by using a phase fitting formula, so as to obtain a target InSAR interference pattern, where the phase fitting formula is related to a horizontal position parameter and an elevation parameter of an observation point.
In some embodiments of the present application, a window parameter obtaining module 410 is configured to perform fitting processing on an original InSAR interferogram to obtain the InSAR interferogram to be corrected; sliding the set initial window on the InSAR interferogram to be corrected according to the sliding step length to obtain a sliding window in an adjacent state and the initial window; and respectively calculating the window parameters corresponding to the sliding window and the initial window.
In some embodiments of the present application, a window size correction module 420 is configured to combine the sliding window and the initial window to obtain a combined window size if it is determined that the window parameter meets the preset condition, where the combined window size is one window in the InSAR interferogram to be corrected; and if the window parameters are confirmed not to meet the preset conditions, taking the sliding window as one window in the InSAR interferogram to be corrected.
In some embodiments of the present application, the window size correction module 420 is configured to confirm that the topographic correlation coefficients corresponding to the sliding window and the initial window are both greater than a first threshold, the phase values of the spatial autocorrelation coefficients corresponding to the sliding window and the initial window are the same in sign, and the difference between the phase gradients corresponding to the sliding window and the initial window is less than a second threshold.
In some embodiments of the present application, the phase correction module 430 is configured to calculate, according to the phase fitting formula, a differential interference phase observation value of an observation point in each window in the interference pattern after the window correction; and correcting the initial interference phase according to the differential interference phase observation value to obtain the target InSAR interferogram.
In some embodiments of the present application, the phase fitting formula is obtained by determining parameters to be estimated in the phase fitting formula by using a least square method based on observed data; wherein the observation data includes: the observation point coordinates and the phase difference value, the observation point coordinates include: a horizontal position parameter and an elevation parameter.
It will be clear to those skilled in the art that, for convenience and brevity of description, reference may be made to the corresponding procedure in the foregoing method for the specific working procedure of the apparatus described above, and this will not be repeated here.
Some embodiments of the present application also provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the operations of the method according to any of the above-described methods provided by the above-described embodiments.
Some embodiments of the present application also provide a computer program product, where the computer program product includes a computer program, where the computer program when executed by a processor may implement operations of a method corresponding to any of the above embodiments of the above method provided by the above embodiments.
As shown in fig. 6, some embodiments of the present application provide an electronic device 500, the electronic device 500 comprising: memory 510, processor 520, and a computer program stored on memory 510 and executable on processor 520, wherein processor 520 may implement a method as in any of the embodiments described above when reading the program from memory 510 and executing the program via bus 530.
Processor 520 may process the digital signals and may include various computing structures. Such as a complex instruction set computer architecture, a reduced instruction set computer architecture, or an architecture that implements a combination of instruction sets. In some examples, processor 520 may be a microprocessor.
Memory 510 may be used for storing instructions to be executed by processor 520 or data related to execution of the instructions. Such instructions and/or data may include code to implement some or all of the functions of one or more of the modules described in embodiments of the present application. The processor 520 of the disclosed embodiments may be configured to execute instructions in the memory 510 to implement the methods shown above. Memory 510 includes dynamic random access memory, static random access memory, flash memory, optical memory, or other memory known to those skilled in the art.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
Claims (8)
1. A method of atmospheric delay error correction, comprising:
Acquiring window parameters of each window in an interferometric synthetic aperture radar (InSAR) interferogram to be corrected, wherein the window parameters comprise: terrain correlation coefficients, spatial autocorrelation coefficients, and phase gradients; wherein the window comprises: the method comprises the steps of setting an initial window and sliding the initial window on the InSAR interferogram to be corrected according to a sliding step length to obtain sliding windows in adjacent states;
Comparing the window parameters with preset conditions, and determining the size of each window in the InSAR interferogram to be corrected to obtain a window corrected interferogram;
Correcting an initial interference phase in the interference pattern after window correction through a phase fitting formula to obtain a target InSAR interference pattern, wherein the phase fitting formula is related to a horizontal position parameter and an elevation parameter of an observation point;
The preset conditions include: the topographic correlation coefficients corresponding to the sliding window and the initial window are both larger than a first threshold value, the phase value signs of the spatial autocorrelation coefficients corresponding to the sliding window and the initial window are the same, and the difference value of the phase gradients corresponding to the sliding window and the initial window is smaller than a second threshold value;
The determining the size of each window in the InSAR interferogram to be corrected by comparing the window parameters with preset conditions comprises the following steps: if the window parameters are confirmed to meet the preset conditions at the same time, combining the sliding window and the initial window to obtain a combined window size, wherein the combined window size is one window in the InSAR interferogram to be corrected; and if the window parameter is confirmed not to meet one of the preset conditions, taking the sliding window as an independent window in the InSAR interferogram to be corrected.
2. The method of claim 1, wherein the obtaining window parameters for each window in the interferometric synthetic aperture radar InSAR interferogram to be corrected comprises:
and fitting the original InSAR interferogram to obtain the InSAR interferogram to be corrected.
3. The method of any one of claims 1-2, wherein correcting the initial interferometric phase in the window-corrected interferogram by a phase fitting formula to obtain a target InSAR interferogram comprises:
Calculating a differential interference phase observation value of an observation point in each window in the interference diagram after window correction through the phase fitting formula;
and correcting the initial interference phase according to the differential interference phase observation value to obtain the target InSAR interferogram.
4. The method of any of claims 1-2, wherein the phase fitting equation is derived from the observed data after determining parameters to be estimated in the phase fitting equation using a least squares method; wherein the observation data includes: the observation point coordinates and the phase difference value, the observation point coordinates include: a horizontal position parameter and an elevation parameter.
5. An apparatus for atmospheric delay error correction, the apparatus for performing the method of claim 1, comprising:
the window parameter acquisition module is used for acquiring window parameters of each window in the InSAR interferogram to be corrected, wherein the window parameters comprise: terrain correlation coefficients, spatial autocorrelation coefficients, and phase gradients;
The window size correction module is used for determining the size of each window in the InSAR interferogram to be corrected by comparing the window parameters with preset conditions to obtain a window corrected interferogram;
The phase correction module is used for correcting the initial interference phase in the interference pattern after window correction through a phase fitting formula to obtain a target InSAR interference pattern, wherein the phase fitting formula is related to the horizontal position parameter and the elevation parameter of the observation point.
6. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a computer program, wherein the computer program when run by a processor performs the method according to any of claims 1-4.
7. An electronic device comprising a memory, a processor, and a computer program stored on the memory and running on the processor, wherein the computer program when run by the processor performs the method of any one of claims 1-4.
8. A computer program product, characterized in that the computer program product comprises a computer program, wherein the computer program, when run by a processor, performs the method according to any of claims 1-4.
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