Time sequence processing method and device for distributed target InSAR with enhanced space-time coherence

A processing method and coherence technology, applied in the directions of measurement devices, radio wave reflection/re-radiation, and utilization of re-radiation, etc., can solve the problems of space-time coherence estimation error propagation, failure, and large space-time coherence estimation errors, etc., to achieve Effect of Uncertainty Reduction

Active Publication Date: 2019-11-05
HOHAI UNIV
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Problems solved by technology

[0005] At present, distributed target deformation monitoring mainly uses spatio-temporal coherence as the quality control data processing method, but the uncertainty of spatio-temporal coherence estimation will cause error propagation, making distributed target InSAR timing technology deviate from millimeter-level accuracy
Especially in low-coherence areas, the estimation error of space-time coherence is larger, which easily leads to the complete failure of the technology

Method used

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  • Time sequence processing method and device for distributed target InSAR with enhanced space-time coherence
  • Time sequence processing method and device for distributed target InSAR with enhanced space-time coherence
  • Time sequence processing method and device for distributed target InSAR with enhanced space-time coherence

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Embodiment approach 1

[0058] Embodiment 1: a distributed target InSAR timing processing method with enhanced spatio-temporal coherence, the specific steps are as follows (such as figure 1 shown):

[0059] 1) InSAR preprocessing. Geometric registration is performed on N single-type complex SAR data sequences on the basis of precise orbits and external digital elevation models, and single-view complex image data stacks are obtained. After radiometrically correcting the SAR image, a common main image is selected, and the remaining N-1 SAR images are interfered, and the external DEM is used to remove the topographic phase contribution of the interferometric image.

[0060] It should be noted that the method of the present invention is applicable to any spaceborne SAR data set, and the N-1 images after interference are differentiated to obtain all N(N-1) / 2 images. Therefore, this is a timing processing method that does not lose interfering information.

[0061] 2) Selection of homogeneous points. De...

Embodiment approach 2

[0076] On the basis of the above embodiment, after step 5) estimates the covariance matrix for each DS candidate point in space one by one, the following bootstrapping estimator is used to weaken the error of the spatial coherence estimation in the covariance matrix, for each The covariance matrix of spatial pixels in the coherence matrix To correct, the expression is as follows:

[0077]

[0078] where R represents the bootstrapping replication number, Represents the coherence matrix samples estimated at each bootstrapping replication. Next, average the variance-reduced variance over all the bias-corrected neighborhood coherence matrix samples:

[0079]

[0080] Optimize the phase using the corrected covariance matrix as follows:

[0081] Obtaining Optimal Phases of Time Series Based on a Maximum Likelihood-Eigenvalue Decomposition Estimator

[0082]

[0083] in Indicates the inversion of the coherence matrix, Indicates the product of Hadamard, Represents...

Embodiment approach 3

[0092] On the basis of the above embodiments, this embodiment uses the Floyd-Warshall multi-source shortest path algorithm in graph theory to select the optimal sub-path of the starting point p and the ending point q.

[0093] First, the PS points are used to form edges with Delaunay triangulation, the purpose of which is to obtain the starting point p and end point q of each edge; this requires first exploring all edges of M PS points. Because the farther the distance between the two points, the more serious the interference from the atmosphere, etc., so the distance needs to be restricted in advance, for example, less than 2000 meters. Estimate the temporal coherence of at most M(M-1) / 2 constrained edges in order to determine the weight of the shortest path algorithm:

[0094]

[0095] where K represents the number of interferograms (single or multi-primary image temporal network), e p,q Indicates the double-difference phase of edges p, q. Convert temporal coherence to ...

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Abstract

The invention discloses a time sequence processing method and device for a distributed target InSAR with enhanced space-time coherence. The method comprises the steps of carrying out threshold separation on a permanent scatterer (PS) and a distributed scatterer (DS) on the basis of an obtained single complex image data stack; performing phase stability analysis on separated PS candidate points bymeans of a StaMPS approach to obtain PS points; carrying out covariance matrix estimation on DS candidate points one by one through a maximum likelihood estimator and refining a covariance matrix through a bootstrapped coherence estimator; performing time sequence phase optimization on each DS candidate point; selecting DS points; constructing a two-layer network for the selected PS and DS points;carrying out phase error separation on an unwrapping phase after three-dimensional phase unwrapping is performed on the PS points and the DS points; utilizing the maximum likelihood estimator and a phase model to estimate geophysical parameters. The method can reduce the uncertainty of InSAR time sequence analysis caused by coherence loss and an ill-conditioned matrix, improve the quality controlof time sequence data processing and thus improve the estimation precision and reliability of products.

Description

technical field [0001] The invention belongs to the field of geodesy, in particular to the field of InSAR time series analysis, specifically a distributed target InSAR time series processing method and device with enhanced spatio-temporal coherence, suitable for high spatial resolution, high High-precision deformation detection. Background technique [0002] Due to its all-day and all-weather observation capabilities and high spatial resolution, InSAR technology has become one of the indispensable research methods for sensing the processes and changes of the earth system today. Since the French scholar Massonnet published in Nature in 1993 that InSAR obtained the coseismic deformation field of Landers in the United States, the application scope of InSAR for earth observation has been continuously expanded. According to the physical significance of its observations, the research objects penetrate into glacier hydrology, seismology, volcanology, environmental science, geologi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S13/90
CPCG01S13/9023
Inventor 蒋弥
Owner HOHAI UNIV
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