CN115629384A - Correction method of time sequence InSAR error and related equipment - Google Patents
Correction method of time sequence InSAR error and related equipment Download PDFInfo
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Abstract
The invention provides a method for correcting a time sequence InSAR error and related equipment, wherein the method for correcting the time sequence InSAR error comprises the following steps: step 1, acquiring an InSAR time sequence phase of a research area; step 2, establishing a combined model for the space trend error, the terrain related error and the deformation signal in the InSAR time sequence phase based on the space-time characteristics of the multi-source signals, and solving model parameters in the combined model to obtain the space trend error and the terrain related error; step 3, subtracting the space trend error and the terrain related error from the InSAR time sequence phase to obtain the corrected InSAR time sequence deformation; the problem that various errors are easily affected by deformation or other error signals when being processed independently is effectively solved, accurate estimation of atmospheric delay and orbit errors is achieved, and accuracy and reliability of time sequence InSAR earth surface deformation measurement are remarkably improved.
Description
Technical Field
The invention relates to the technical field of surface deformation measurement, in particular to a method for correcting time sequence InSAR errors and related equipment.
Background
The time-series Synthetic Aperture Radar (SAR) interferometry can obtain the surface deformation result of a research area with long time series and high spatial resolution by analyzing a time-series SAR image, and provides important data support for interpretation, analysis and prevention of related geological disasters. However, due to the influence of factors such as atmospheric delay (including turbulent atmosphere and stratified atmosphere) and orbit errors, the deformation measurement accuracy of the time sequence InSAR technology is difficult to be effectively guaranteed, and further the subsequent application analysis is influenced. In the case where accurate external meteorological data (e.g., temperature, barometric pressure, etc.) or other geodetic data (e.g., global Navigation Satellite System (GNSS) Global Navigation System and leveling data) are available, atmospheric and orbital errors in the InSAR observations can be effectively attenuated. However, these external data are generally difficult to acquire, and error correction can be performed only based on different spatio-temporal characteristics of signals such as distortion, atmospheric delay, and track error in the InSAR observed value. For example, orbital errors can be modeled and corrected spatially using second order polynomials, layered atmospheres can be modeled and corrected by correlation analysis with terrain, and turbulent atmospheres can be suppressed by spatial and temporal filtering. Although the existing research has carried out relevant work for correcting and suppressing various errors, most of the research is to model and correct certain types of errors on the premise of assuming that other errors have small influence. However, in practical situations, orbit errors, turbulent atmosphere and stratified atmosphere often exist simultaneously, if only one type of errors are modeled and corrected, the correction accuracy is influenced by other error signals, and finally the reliability of the time sequence InSAR deformation measurement is reduced.
Disclosure of Invention
The invention provides a method for correcting time sequence InSAR errors and related equipment, and aims to solve the problem that various errors are easily affected by deformation or other error signals when being processed independently and improve the precision and reliability of time sequence InSAR deformation measurement.
In order to achieve the above object, the present invention provides a method for correcting timing InSAR errors, comprising:
step 1, acquiring an InSAR time sequence phase of an InSAR interferogram;
and 3, subtracting the space trend error and the terrain related error from the InSAR time sequence phase to obtain the corrected InSAR time sequence deformation.
Further, step 2 comprises:
modeling the spatial trend error by using a first-order polynomial to obtain a polynomial fitting coefficient equation;
characterizing the terrain related error by using a linear model to obtain a linear equation coefficient equation;
constructing a virtual observation equation for the deformation signal by utilizing a third-order polynomial function;
and (4) simultaneously establishing a polynomial fitting coefficient equation, a linear equation coefficient equation and a virtual observation equation to obtain a combined model.
Further, the model parameters in the joint model include time sequence deformation of all pixels, polynomial fitting coefficients of spatial trend errors at all pixels, and linear equation coefficients of terrain-related errors at all pixels.
Further, the step 2 further includes:
randomly selecting one pixel from all pixels as a target pixel;
at the moment of timeBy target pixelThe center is taken as the sizeThe polynomial fitting coefficient equation is established as follows:
wherein,for an InSAR phase observation at each pixel within the window,for the phase of the deformation at each point,is composed ofThe integer number within the interval is such that,in order to have a terrain-dependent error phase,、、fitting coefficients for the polynomial;
vector the observed value in the above formulaIncorporating the total observed value vectorIn (2), then the corresponding coefficient matrixWill increaseLine, each line and the above formula medium observation value vectorCorresponding to the elements of (2), most elements in each row are 0, and only correspond to the model parameter vectorThe column corresponding to the middle element is not 0, and the value is the matrix of the middle and coefficient in the above formulaThe corresponding element of the corresponding row.
Further, the step 2 further includes:
randomly selecting one pixel from all pixels as a target pixel;
at the moment of timeBy target pixelIs taken as the center and has the size ofThe linear equation coefficient equation is established:
wherein,for an InSAR phase observation at each pixel within the window,in order to change the phase of the deformation,in order to trend the phase of the signal,is a window intervalThe number of the integers in (a) is,is a pixelAnd picture elementThe difference in elevation between the two,、is the coefficient of a linear equation;
vector the observed value in the above formulaIncorporation of the Total observed value vectorIn (3), then the corresponding coefficient matrixWill increaseLine, each line and the above formula medium observation value vectorCorresponds to the elements of (1), most elements in each row are 0, and only correspond to the model parameter vectorThe corresponding column of the middle element is not 0, and the value is the coefficient matrix in the formulaThe corresponding element of the corresponding row.
Further, the step 2 further includes:
randomly selecting one pixel from all pixels as a target pixel;
at the moment of timeBy target pixelTaking a time window with the size as the center, and constructing a virtual observation equation as follows:
wherein,is a variable of a parameter of the intermediate model,and withThe difference between the values of the two values is equal to 0,in order to change the shape of the time sequence,to shape the time sequenceThe fitting value of the cubic polynomial of (c),、、are respectively the firstScene SAR image and secondTime difference between scene SAR image momentsScene SAR image and scene SAR imageTime difference between scene SAR image momentsScene SAR image and secondThe time difference between the moments of the scene SAR images,。
further, the step 2 further includes:
the additional virtual observation equation is established by using the prior information as follows:
adding the virtual observation equation to the total observation vectorAnd in the corresponding coefficient matrixAdd one row in.
Further, the simultaneous polynomial fitting coefficient equation, the linear equation coefficient equation and the virtual observation equation obtain a combined model, which includes:
based on a polynomial fitting coefficient equation, a linear equation coefficient equation, a virtual observation equation and an additional virtual observation equation, establishing a combined model of a spatial trend error, a terrain correlation error and a deformation signal in an InSAR time sequence phase as follows:
wherein,to be the total vector of observations,is a matrix of coefficients, and is,are model parameters.
The present invention also provides a computer-readable storage medium for storing a computer program for implementing the above-described method for correcting timing InSAR errors by executing the computer program.
The invention also provides a device for correcting the time sequence InSAR error, which is used for realizing the method for correcting the time sequence InSAR error and comprises the following steps:
a memory and a processor;
the memory is used for storing a computer program;
the processor is for executing the computer program stored by the memory.
The scheme of the invention has the following beneficial effects:
the method constructs a combined model of spatial trend errors, terrain related errors and deformation signals in the InSAR time sequence phase based on the time-space characteristics of multi-source signals such as deformation, atmospheric delay and orbit errors, effectively solves the problem that various errors are easily affected by deformation or other error signals when being processed independently, realizes accurate estimation of atmospheric delay and orbit errors, and obviously improves the precision and reliability of surface deformation measurement of the time sequence InSAR.
Other advantages of the present invention will be described in detail in the detailed description that follows.
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FIG. 1 is a flow diagram of an embodiment of the present invention;
fig. 2 is a comparison diagram of the InSAR time sequence deformation results at the funnel center obtained by different methods in the embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted", "connected" and "connected" are to be construed broadly, e.g., as being either a locked connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides a method for correcting time sequence InSAR errors and related equipment aiming at the existing problems.
Specifically, the embodiment of the invention performs combined correction on the time sequence InSAR atmospheric delay and the orbit errors, wherein the orbit errors are considered as low-frequency signals in space, and meanwhile, the turbulent atmospheric errors are in a small space range, such as 1 multiplied by 1km 2 It may also be considered a low frequency signal, and thus the orbit error and turbulent atmosphere are collectively referred to as a trend error in the embodiments of the present invention. For the spatial trend error at a certain pixel point, a polynomial fitting modeling can be performed by using observed values within a certain spatial range, such as 5 × 5 pixels. The layered atmosphere is mainly related to local terrains and is called as a terrain related error, for the terrain related error at a certain pixel point, linear fitting modeling can be performed on an InSAR observed value and the terrain within a certain spatial range, in addition, sudden events such as earthquakes and the like are eliminated, the deformation of the earth surface is a slowly-changing process in time under general conditions, time sequence earth surface deformation can be considered to meet a cubic equation related to time within a certain time range, the assumption is used as a priori constraint condition, and space-time unified modeling is performed on atmospheric delay errors, orbit errors and deformation signals in an InSAR time sequence phase, so that the problem that various errors are easily influenced by deformation or other error signals when being processed independently can be effectively avoided, and the precision and the reliability of time sequence InSAR deformation measurement are improved.
As shown in fig. 1, an embodiment of the present invention provides a method for correcting a timing InSAR error, including:
step 1, acquiring an InSAR time sequence phase of an InSAR interferogram;
and 3, subtracting the space trend error and the terrain related error from the InSAR time sequence phase to obtain the corrected InSAR time sequence deformation.
Specifically, the embodiment of the invention is Based on an SBAS (Satellite-Based Augmentation System) Satellite-Based Augmentation System or a SqueeSAR distribution permanent scatterer Satellite radar monitoring technical method, the orbit error and the atmospheric delay error in an InSAR interferogram do not need to be corrected until the InSAR time sequence phase is obtained, and the subsequent spatial trend error and terrain related error are corrected according to the InSAR time sequence phase.
The track error and the atmospheric delay error exist in the InSAR interferogram, and the essential reason is that the SAR images forming the interferogram contain the corresponding track error and the atmospheric delay error, so that the InSAR time sequence phase obtained based on the InSAR interferogram without track error and atmospheric delay error correction not only contains time sequence deformation but also contains the track error and the atmospheric delay error corresponding to each moment, and therefore, the method is more reasonable for directly carrying out corresponding error correction on the InSAR time sequence phase. Meanwhile, compared with an InSAR interferogram, the data volume of the InSAR time sequence phase can be greatly reduced, and the data processing efficiency is improved.
Specifically, step 2 in the embodiment of the present invention mainly considers the function model establishment in three aspects:
1, for a spatial trend error, in a small window range of 1km multiplied by 1km, modeling can be carried out by utilizing a first-order polynomial related to a position to obtain a polynomial fitting coefficient equation;
2, for terrain related errors, within a certain small window range, a linear model related to terrain can be used for characterization to obtain a linear equation coefficient equation;
for the deformation signal, in a certain space range, the deformation signal is often similar to the space trend error in terms of space characteristics, and the difference is that the deformation signal is also related in a certain time window, so that a virtual observation equation related to time sequence deformation can be established through a time-related third-order polynomial function, and further the virtual observation equation is combined with the function models in 1 and 2, so that the same modeling of space and time of the space trend error, the terrain related error and the time sequence deformation signal is realized.
In the embodiment of the present invention, it is assumed that there is an existing oneNInSAR time sequence phase of each time, the phase of each time isI×JThe size matrix, the model parameters to be solved in the combined model of the embodiment of the present invention include: time sequence deformation of all pixelsPolynomial fitting coefficients of spatial trend errors at all pixelsCoefficient of linear equation of terrain-dependent error at all pixelsIn whichIs shown asAt a time instant.
The model parameters are solved by building a function model, whereby the model parameters in the built function model are solvedIs of a size of(generally, the first scene image is selected as the reference image), the corresponding coefficient matrixColumn number and model parameter vector ofAre consistent in length. At this time, if the model parameter solution is requiredThe key to constructing the coefficient matrix isVector of sum observations。
Specifically, step 2 in the embodiment of the present invention further includes:
taking an example of arbitrarily selecting one pixel from all pixels as a target pixel, a specific process of establishing a coefficient matrix and an observed value vector related to the pixel model parameter at the moment is introduced.
First, a polynomial fitting coefficient equation of the spatial trend error is establishedTime of day, with target pixelIs taken as the center and has the size ofThe InSAR phase in the window can be regarded as the sum of the deformation phase, the space trend error phase and the terrain correlation error phase, wherein the model parameters in the window comprise the deformation phase of each pixelTopography dependent error phaseAnd polynomial fitting coefficients of spatial trend error phase within the windowIn whichIs composed ofInteger within interval, therefore, inSAR phase observation for each pixel within the windowCan be written as:
wherein,for the InSAR phase observation at each pixel within the window,for the phase of the deformation at each point,is composed ofThe integer number within the interval is such that,in order to have a terrain-dependent error phase,、、is a coefficient of a polynomial fit,Trepresenting a matrix transposition.
Vector of observed values in the above formula (2)Incorporating the total observed value vectorIn (2), then the corresponding coefficient matrixWill increaseLines, each line and the vector of observations in equation (2) aboveCorresponding to the elements of (2), most elements in each row are 0, and only correspond to the model parameter vectorThe column corresponding to the middle element is not 0, and the value is the matrix of coefficients in the above formula (2)The corresponding element of the corresponding row.
Specifically, step 2 in the embodiment of the present invention further includes:
establishing a linear fitting coefficient equation of the terrain-related errors inTime and target pixelIs taken as the center and has the size ofThe InSAR phase within the window can also be considered as the sum of the morphed phase, the trend phase, and the terrain-dependent phase, with the difference that the model parameters within the window include the morphed phase at each pointTrend phaseAnd linear fitting coefficients for terrain-dependent errors within the windowWhereinis composed ofInteger within the interval, thus, for InSAR phase observations at each pixel within the windowCan be written as:
wherein,for an InSAR phase observation at each pixel within the window,in order to change the phase of the deformation,in order to trend the phase of the signal,is an integer number within the window interval and,is a pixelAnd a pixelThe difference in elevation between the two electrodes,、is the coefficient of a linear equation;
vector the observed values in the above formula (4)Incorporating the total observed value vectorIn (2), then the corresponding coefficient matrixWill increaseLines, each line and the vector of observations in equation (4) aboveCorresponds to the elements of (1), most elements in each row are 0, and only correspond to the model parameter vectorThe corresponding column of the middle element is not 0, and the value is the coefficient matrix in the above formula (4)The corresponding element of the corresponding row.
It should be noted that, since the spatial dimensions of the spatial trend error and the terrain-related error are generally different, for example, the spatial dimension for modeling the terrain-related error is often related to the actual terrain, and the spatial dimension of the spatial trend error is often in a larger range, the window size model parameters in the process of establishing the above equations (2) and (4) are more extensiveAre generally different. Further, as can be seen from equations (2) and (4), the observed value vectors in the two types of equationsAndwill contain the same observed value, that is to say, for one observed value in InSAR time sequence phaseMay be in the final observation vectorMultiple times. And when the trend phase in the window is modeled in the formula (1), the reference point of the space position is the target pixelIn this case, the constant term in the polynomial coefficient is the trend phase value at the pixel, and the target pixelThe trend phase of (b) may also appear as a model parameter in an equation established at other pixel, namely equation (2); similarly, when the terrain related error in the window is modeled in the formula (3), the reference point of the elevation is the target pixelThe elevation of the target pixel, in which case the constant term in the linear equation coefficient is the terrain related error value of the pixel, and the target pixelThe terrain-related error at (a) may also appear as a model parameter in the equations established at other picture elements, i.e., equation (4). From the analysis, it can be seen that the formulas (2) and (4) established for different pixels contain model parameters of other pixels, so that the model parameter solution of each pixel cannot be performed pixel by pixel, only one large-scale function model about all model parameters at all moments and all pixels can be established, then the model parameters are integrally solved, and the solved model parameters are space trend errors and terrain related errors.
Specifically, step 2 in the embodiment of the present invention further includes:
and (3) assuming that the time sequence deformation is fitted through a cubic polynomial in a certain time window range, namely providing an external constraint condition for the time sequence deformation, and establishing a virtual observation equation related to the time sequence deformation. In general, the virtual observation equation is in the form of "0= coefficient matrix × model parameter vector". For time-series deformation, the model parameter vector is the time-series deformation, so the key point for constructing the virtual observation equation is how to determine a corresponding coefficient matrix according to external constraint conditions.
At the moment of timeBy target pixelThe process of constructing the virtual observation equation is described as follows:
first, with the time of dayAs a center, take the size ofTime window ofThen the corresponding model parameter (time series deformation) vector is. When the temperature is higher than the set temperatureWhen known, the following relationships exist:
coefficient matrixIn the step (1), the first step,、、are respectively the firstScene SAR image and secondTime difference between scene SAR image momentsScene SAR image and secondTime difference between scene SAR image momentsScene SAR image and secondThe time difference between scene SAR image moments, constant terms in cubic polynomial coefficients areDeformation corresponding to the moment. Due to the coefficient matrixIs known, then based on the least square method can obtain
Further, the time sequence deformation can be obtainedFitting value of cubic polynomialIs composed of
Wherein,for the intermediate model parameter variables, the model parameters,andthe difference between the values of the two values is equal to 0,in order to change the shape of the time sequence,to shape the time sequenceThe fitting value of the cubic polynomial of (c),、、are respectively the firstScene SAR image and scene SAR imageTime difference between scene SAR image momentsScene SAR image and secondTime difference between scene SAR image momentsScene SAR image and scene SAR imageThe time difference between the moments of the scene SAR images,。
equation (8) is the time in the method of the present inventionTarget pixelAnd (4) constructing a virtual observation equation. For each moment of each pixel, the formula (A)8) When in the observation vectorAdd a 0 value element to the corresponding coefficient matrixA row is added, and the elements in the row corresponding to the model parameters in the formula (8) are the corresponding elements of the coefficient matrix in the formula (8). It can be seen that, in the modeling process in the similar space and the virtual observation equation in time, for a certain moment, the model parameters of the pixels corresponding to other moments are also included, so that the model parameters at all moments need to be modeled and solved simultaneously.
In addition to the three equation establishment methods described above, additional virtual observation equations may also be established, typically using other a priori information. For example, in some research areas, the deformation range is often smaller than the coverage range of the whole SAR image, so there is a far-field area, which is considered as the far-field area without surface deformation, that is:
similar to equation (8), the above-mentioned virtual observation equation can also be added to the final model parameter solution function model (i.e. the model). This kind of a priori assumption condition is often true because in the process of InSAR data processing, it is inevitable to perform spatial phase unwrapping with a certain point as a reference point in space, that is, the measurement result of the InSAR data itself is a relative result. For a target research area, some areas are manually selected based on prior information, and the deformation of the areas is assumed to be 0, so that the reliability of the combined model in the embodiment of the invention can be further improved.
Based on the formulas (2) and (4)The parameters for solving the model can be obtained from (8) and (9)Vector of observed values ofSum coefficient matrixWhereinSatisfies the following formula
Equation (10) is a combined model of the spatial trend error, the terrain-related error and the deformation signal in the built InSAR time sequence phase, wherein,to be the total vector of observations,in the form of a matrix of coefficients,are model parameters.
Specifically, in the embodiment of the present invention, the coefficient matrix in the formula (10) is usedIs a large coefficient matrix, so the existing sparse least square iterative algorithm is adopted to carry out the step 3 on the model parametersSolving is carried out, and the model parameters in the formula (10) are quickly and accurately solved through the lsmr function in the matlab to obtainTo the corresponding spatial trend error and terrain-related error at each pixel at each instant in time.
Specifically, in step 4, the spatial trend error and the terrain correlation error are subtracted from the original InSAR time sequence phase, so that the corrected high-precision InSAR time sequence deformation is obtained.
In summary, based on the conventional method for obtaining the timing phase of the InSAR, the embodiments of the present invention consider that, within a certain spatial range (e.g., 1km × 1 km), the turbulent atmosphere and the orbit error can be modeled by using a first-order polynomial related to the position; the method can utilize the relation between the layered atmosphere and the local terrain to carry out linear modeling; within a certain time range (such as 1 month), most of the surface deformation can be regarded as a time-dependent smoothing process, and a time-dependent cubic function can be used for fitting; in the InSAR image, the deformation of the far field area is equal to 0, and the prior information can be used as a constraint condition for auxiliary modeling. Based on the 4 kinds of prior information, the invention realizes the combined modeling of different signals such as deformation, atmospheric delay, orbital error and the like in the InSAR time sequence phase, and on the basis, the solution is carried out by using a sparse least square iterative algorithm, so that the high-precision estimation and correction of the atmospheric delay and the orbital error in the InSAR time sequence phase can be realized, and the measurement precision of the InSAR time sequence deformation is further obviously improved; the method breaks through the idea of independently processing various errors by the traditional method, fully considers the time-space characteristics of multi-source signals, and greatly enriches the theory and method system of time sequence InSAR earth surface deformation measurement.
The following simulation experiments further illustrate the embodiments of the present invention:
InSAR time sequence deformation at 22 moments is obtained through simulation by an SBAS method, the space size of a deformation field is 600 x 600 pixels, and the spatial resolution of each pixel is 100m x 100m. Wherein the deformation is characterized by funnel shape in space, and the change trend of each point in time is logarithmic, i.e. the deformation is characterized byDeformation ofIn units of meters, timeRepresents the time difference relative to a reference time in days; the orbit error in the whole deformation field range at each moment is simulated, wherein the maximum magnitude of the orbit error is 10 radians (about 4.4 centimeters for a c wave band), and the orbit error shows that the three-dimensional trend direction is random at each moment in space; the turbulence atmospheric error at each moment can be simulated by using a fractal function with a fractal dimension of 2.2, and the maximum magnitude is 10 radians; regarding the layered exhaust steam related to the terrain, considering that the proportionality coefficients between the layered atmosphere and the terrain are possibly inconsistent in different regions of the space, the proportionality coefficients between the layered atmosphere phase and the terrain in different regions of the space are simulated by using a fractal function with a fractal dimension of 2.2 in a simulation experiment, and then the layered atmosphere component in the simulation data is obtained by multiplying the proportionality coefficient obtained through simulation by real DEM Data (DEM) global Digital Elevation data; and adding the simulated InSAR time sequence deformation, the orbit error, the turbulent atmosphere and the layered atmosphere to obtain the InSAR time sequence phase used by the simulation test.
In order to compare the advantages of the embodiment of the invention, the simulated InSAR time sequence phase is used as an observed value, and the method provided by the embodiment of the invention and the traditional method are respectively utilized to correct the atmospheric delay error and the orbit error in the InSAR time sequence phase. The conventional method is that in the whole image, a deformation region is masked, a trend phase and a terrain-related phase are jointly modeled and solved by using a non-deformation region, and then the trend phase and the terrain-related phase of the deformation region are forward calculated by using model parameters obtained by solving, so that the correction of related errors in the whole image can be realized, and as shown in fig. 2, the InSAR time sequence deformation results obtained by different methods at the center of a funnel show that the method provided by the embodiment of the invention is more accurate than the InSAR time sequence deformation results obtained by the conventional method.
The embodiment of the invention also provides a computer-readable storage medium for storing a computer program and implementing the method for correcting the timing InSAR error by executing the computer program.
The embodiment of the invention also provides a device for correcting the time sequence InSAR error, which is used for realizing the method for correcting the time sequence InSAR error and comprises the following steps:
a memory and a processor;
the memory is used for storing a computer program;
the processor is for executing the computer program stored by the memory.
While the foregoing is directed to the preferred embodiment of the present invention, it will be appreciated by those skilled in the art that various changes and modifications may be made therein without departing from the principles of the invention as set forth in the appended claims.
Claims (10)
1. A method for correcting time sequence InSAR errors is characterized by comprising the following steps:
step 1, acquiring an InSAR time sequence phase of an InSAR interferogram;
step 2, establishing a combined model for the spatial trend error, the terrain related error and the deformation signal in the InSAR time sequence phase based on the space-time characteristics of the multi-source signals, and solving model parameters in the combined model to obtain the spatial trend error and the terrain related error;
and 3, removing the space trend error and the terrain related error in the InSAR time sequence phase to obtain the corrected InSAR time sequence deformation.
2. The method for correcting timing InSAR error according to claim 1, wherein the step 2 further comprises:
modeling the space trend error by using a first-order polynomial to obtain a polynomial fitting coefficient equation;
characterizing the terrain related error by using a linear model to obtain a linear equation coefficient equation;
constructing a virtual observation equation for the deformation signal by utilizing a third-order polynomial function;
and simultaneously establishing the polynomial fitting coefficient equation, the linear equation coefficient equation and the virtual observation equation to obtain a combined model.
3. The method for correcting the timing InSAR error according to claim 2, wherein the model parameters in the joint model include timing deformation of all pixels, polynomial fitting coefficients of spatial trend errors at all pixels, and linear equation coefficients of terrain-related errors at all pixels.
4. The method for correcting timing InSAR error according to claim 3, wherein the step 2 further comprises:
randomly selecting one pixel from all pixels as a target pixel;
at the moment of timeWith the target pixelIs taken as the center and has the size ofThe polynomial fitting coefficient equation is established as follows:
wherein,for an InSAR phase observation at each pixel within the window,for the phase of the deformation at each point,is composed ofThe number of integers in the interval (a) is,in order for the terrain-dependent error phase to be,、、fitting coefficients for the polynomial;
vector the observed values in the above equationIncorporating the total observed value vectorIn (3), then the corresponding coefficient matrixWill increaseLine, each line and the above formula medium observation value vectorCorresponding to the elements of (2), most elements in each row are 0, and only correspond to the model parameter vectorThe column corresponding to the middle element is not 0, and the value is the matrix of the middle and coefficient in the above formulaThe corresponding element of the corresponding row.
5. The method for correcting timing InSAR error according to claim 4, wherein said step 2 further comprises:
randomly selecting one pixel from all pixels as a target pixel;
at the moment of timeWith the target pixelIs taken as the center and has the size ofThe linear equation coefficient equation is established:
wherein,for an InSAR phase observation at each pixel within the window,in order to change the phase of the deformation,in order to trend the phase of the signal,is an integer number within the window interval and,is a pixelAnd a pixelThe difference in elevation between the two electrodes,、is the coefficient of a linear equation;
vector the observed value in the above formulaIncorporation of the Total observed value vectorIn (2), then the corresponding coefficient matrixWill increaseLines, each line and the observed value vector in the above formulaCorresponding to the elements of (2), most elements in each row are 0, and only correspond to the model parameter vectorThe corresponding column of the middle element is not 0, and the value is the coefficient moment in the formulaMatrix ofThe corresponding element of the corresponding row.
6. The method for correcting timing InSAR error according to claim 5, characterized in that said step 2 further includes:
randomly selecting one pixel from all pixels as a target pixel;
at the moment of timeWith the target pixelTaking a time window with the size as the center, and constructing a virtual observation equation as follows:
wherein,,for the intermediate model parameter variables, the model parameters,andthe difference between the values of the two values is equal to 0,in order to change the shape of the time sequence,to shape the time sequenceThe fitting value of the cubic polynomial of (c),、、are respectively the firstScene SAR image and scene SAR imageTime difference between scene SAR image momentsScene SAR image and secondTime difference between scene SAR image momentsScene SAR image and secondThe time difference between the scene SAR image instants,。
7. the method for correcting timing InSAR error according to claim 6, wherein the step 2 further comprises:
the additional virtual observation equation is established by using the prior information as follows:
8. The method for correcting timing InSAR error according to claim 7, wherein the simultaneous fitting of the polynomial fitting coefficient equation, linear equation coefficient equation and virtual observation equation to obtain a combined model comprises:
based on the polynomial fitting coefficient equation, the linear equation coefficient equation, the virtual observation equation and the additional virtual observation equation, establishing a combined model of the space trend error, the terrain correlation error and the deformation signal in the InSAR time sequence phase as follows:
9. A computer-readable storage medium storing a computer program for implementing the method for correcting timing InSAR error of any one of claims 1 to 8 by executing the computer program.
10. A correction device for timing InSAR errors, for implementing the correction method for timing InSAR errors according to any one of claims 1 to 8, characterized in that it comprises:
a memory and a processor;
the memory is used for storing a computer program;
the processor is configured to execute the computer program stored by the memory.
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