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Interference baseline estimation method based on SRTM DEM

A baseline estimation and baseline technology, applied in the field of signal processing, can solve the problems of low baseline accuracy and poor baseline estimation accuracy, and achieve the effect of high accuracy and reduced calculation amount

Inactive Publication Date: 2019-01-18
XIDIAN UNIV
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AI Technical Summary

Problems solved by technology

In the baseline estimation method based on the satellite state vector, the position and velocity vector information of the orbit is directly used for baseline estimation. This baseline estimation method has the following disadvantages: when the orbits of the two interferometric SAR images are real-time orbits, the baseline estimation accuracy is very poor
It is a blind estimation method, which is only suitable for flat areas and uses orbital parameters for calculation, so the estimated baseline accuracy is not high

Method used

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  • Interference baseline estimation method based on SRTM DEM
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  • Interference baseline estimation method based on SRTM DEM

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Embodiment 1

[0029] The satellite orbit state vector method is commonly used in radar interference processing. Although it is the simplest and most commonly used, it is greatly affected by the orbit, especially under real-time orbit conditions, and cannot guarantee the accuracy of baseline estimation. Estimating the baseline based on the self-information of the interferogram is only suitable for areas with flat terrain, and the estimation error is relatively large under special conditions such as earthquakes. In practical applications, it is necessary to quickly and accurately obtain terrain information under certain natural disaster conditions. The present invention is aimed at this requirement. After discussion and experiments, an interference baseline estimation method based on SRTM DEM is proposed. see figure 1 , including the following steps:

[0030] (1) Preprocessing of orbit fitting: According to different parameter file formats, two SAR images and trajectory data are obtained, in...

Embodiment 2

[0039] The technical scheme of the interferometric baseline estimation method based on SRTM DEM is the same as embodiment 1, described in step (1) with Lagrangian interpolation method to track fitting, comprises the following steps:

[0040] (1a) Obtaining orbital information: According to the format of different parameter files, the orbital parameters of two interferometric SAR images are read, including satellite orbital position and velocity information.

[0041] (1b) Perform Lagrangian interpolation fitting on the orbit: Lagrangian interpolation fitting polynomial expression is as follows:

[0042]

[0043]

[0044] where x j Represents the independent variable, that is, the position of the satellite state vector to be fitted, y j represents the value corresponding to the fitting point, l j (x) is the Lagrangian interpolation basis function.

[0045] If interpolation processing is not performed, the singular values ​​in the satellite orbit data will affect the acc...

Embodiment 3

[0047] The technical solution of the interference baseline estimation method based on SRTM DEM is the same as that in Embodiment 1-2. In step (2), the method of reverse positioning is used to obtain the elevation value of SRTM DEM on the inclined plane, including the following steps:

[0048] (2a) Coordinate transformation: SRTM DEM provides three-dimensional coordinates of ground plane latitude, longitude and elevation, while the information of each point in the slant distance plane is usually implemented in the WGS84 (World Geodetic System-1984 Coordinate System) coordinate system. In particular, in order to find the corresponding position of the SRTM DEM on the slant distance plane, the coordinates must be transformed, and the transformation relationship is shown as follows:

[0049]

[0050] X, Y, Z represent the coordinates in the WGS84 coordinate system, B represents the north latitude, L represents the longitude, H is the height, N is the radius of curvature, a is th...

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Abstract

The invention discloses an interference baseline estimation method based on SRTM DEM, which solves the problem of poor accuracy of real-time orbit rapid generation DEM. Realization steps: real-time trajectory fitting of two interferometric SAR images is carried out by Lagrange interpolation; the elevation value of SRTM DEM on the oblique plane is obtained; the unwrapped phase of two SAR interferometric images is used to perform phase-elevation conversion, to obtain the elevation value of the interference image in the oblique plane; The height error on the oblique plane is obtained by subtracting the height of SRTM DEM on the oblique plane from the height of the oblique plane obtained by interferometry of two SAR images; the baseline error in the scene is obtained by using the relationshipamong the fuzzy height, elevation error and baseline error; the real-time orbit error is corrected by the baseline error, and the DEM is reconstructed by the corrected orbit information; the baselineestimation results are verified by comparing the DEM with SRTM DEM. The invention obviously alleviates the precision loss of DEM reconstruction of real-time orbit, effectively observes topography andgeomorphology, and can be used for signal processing such as InSAR.

Description

technical field [0001] The invention belongs to the technical field of signal processing, and in particular relates to baseline estimation of Interferometric Synthetic Aperture Radar (InSAR) images, in particular to an interferometric baseline estimation method based on SRTM DEM, which can be used for processing InSAR and other signals. Background technique [0002] The digital elevation model (DEM) is the main product of the interferometric synthetic aperture radar technology. It is the elevation points evenly distributed on the grid obtained by the interferometric phase through elevation conversion and geocoding. It can show the fluctuation state of the actual terrain. All have broad application prospects. Baseline is an important parameter in InSAR. It determines the selection of effective interferometric image pairs, and its accuracy also affects the accuracy of the final extracted surface elevation or deformation. Research on high-precision interferometric SAR baselin...

Claims

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Application Information

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IPC IPC(8): G06T7/13G06F17/18
CPCG06F17/18G06T7/13
Inventor 李真芳鲁焕张则玺赵纪伟
Owner XIDIAN UNIV
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