Multi-image joint registration method based on least square estimation

A least squares method and least squares technology, applied in the field of signal processing, can solve the problems of poor registration accuracy, low registration accuracy of auxiliary images, and no consideration of auxiliary images, etc., to achieve the effect of improving registration accuracy

Active Publication Date: 2018-04-20
XIDIAN UNIV
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  • Abstract
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  • Application Information

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Problems solved by technology

In the SMC method, one image is selected as the main image, and other images are registered with it respectively. This registration method has two disadvantages: when the time baseline, space baseline or Doppler center frequency difference between the auxiliary image and the main image When it is large, the registration accuracy is very poor; the transfer of registration error between auxiliary images is not considered, resulting in low registration accuracy between auxiliary images
In the SWC method, the minimum spanning tree method is used to connect the primary and secondary images in the time baseline-space baseline two-dimensional plane, and there is severe temporal and / or spatial decoherence in image pairs with long temporal and / or spatial baselines, which is very It is difficult to fine-register these images
In addition, due to the error propagation effect, although all auxiliary images can be registered with the main image with a small registration error, the registration accuracy of image pairs not connected by the minimum spanning tree method will be poor
Therefore, the registration accuracy of the SMC and SWC methods cannot be guaranteed

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Embodiment 1

[0026] The commonly used multi-image registration method in radar interferometric processing is SMC, but this method is greatly affected by temporal and / or spatial decoherence and error propagation effects, resulting in low registration accuracy. When the radar platform scans the same scene area on the ground multiple times, it will form multiple SAR images for this scene area. Due to the different motion trajectories of the observation radar platform, the images formed by multiple observations of the same area target will drift in the same resolution unit. Scaling or rotation effects cause small pixel deviations in the distance and azimuth directions of these images, and the phase difference cannot reflect the height fluctuation of the ground, so it is naturally impossible to invert the DEM of the scene area. Therefore, the interferometric multi-image registration process must be performed to match multiple SAR images well, and the pixels at the corresponding positions corresp...

Embodiment 2

[0036] The multi-image joint registration method based on least squares estimation is the same as embodiment 1, and connects all SAR images with the Delaunay triangulation method described in step (1), including the following steps:

[0037] (1a) In the space baseline-time baseline two-dimensional plane, use the Delaunay triangulation method to connect all the SAR images in the image set.

[0038] (1b) Keep all SAR images in the image set within a single Delaunay triangulation.

[0039] (1c) Optimize the network by threshold comparison: set appropriate spatial and temporal baseline thresholds, use the threshold comparison method, discard arcs with longer spatial and / or temporal baselines to optimize the Delaunay triangulation, and retain as much coherence as possible Stronger image pairs.

[0040] After connecting all SAR images with optimized Delaunay triangulation, image pairs with strong coherence can be kept as much as possible, while image pairs with longer space and / or ...

Embodiment 3

[0042] The multi-image joint registration method based on least squares estimation is the same as embodiment 1-2. In step (2), it is estimated that the registration offset of the SAR image pair after optimizing the Delaunay triangulation network connection includes the following steps:

[0043] (2a) Define the registration offset of the connected image pairs: Suppose there are M SAR image pairs connected by the optimized Delaunay triangulation, then the registration offsets of the M connected image pairs in the distance and azimuth directions are expressed as :

[0044] δa=[δa 1 ,…,δa M ] T (1)

[0045] δr=[δr 1 ,…,δr M ] T (2)

[0046] Among them, δa 1 ,…,δa M is the registration offset of the M connected image pairs in the azimuth direction, which is stored in the vector δa; δr 1 ,…,δr M is the registration offset of the M connected image pairs in the upward distance, which is stored in the vector δr; the superscript T represents the transposition of the vector....

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Abstract

The invention discloses a multi-image joint registration method based on least square estimation. The method solves the problem of improving multi-image registration precision in signal processing ofPS-InSAR and the like, and includes the realization steps of: using Delaunay triangulation to connect all SAR images in an image set, and optimizing the Delaunay triangulation; using an InSAR registration method to estimate registration offsets of already connected SAR image pairs; selecting a reference image in the image set, and selecting certain uniformly-distributed control points on the reference image; using a least square method to estimate registration offsets of all auxiliary images relative to the reference image at each control point; constructing deviation functions of all the auxiliary-image registration offsets, and estimating registration offsets of all the auxiliary images relative to the reference image; and carrying out re-sampling on all the auxiliary images by the offsets to complete multi-image joint registration. The method significantly mitigates time and space decoherence and error propagation effect impacts, improves multi-image joint registration precision, ishigher in a region coincidence degree of the reference image and the auxiliary images at the same pixel, and can be used for signal processing of the PS-InSAR and the like.

Description

technical field [0001] The invention belongs to the technical field of signal processing, and in particular relates to multi-image registration of interferometric synthetic aperture radar InSAR images, in particular to a multi-image joint registration method based on least square estimation, which can be used for signal processing of PS-InSAR and the like. Background technique [0002] The application of interferometric synthetic aperture radar InSAR is extremely extensive, and the most direct application is to obtain the digital elevation map DEM. InSAR signal processing includes interferometric SAR image pair registration, interferometric phase filtering and interferometric phase unwrapping. The absolute phase obtained by unwrapping is used to invert the elevation information of the scene target and obtain its DEM. Interferometric SAR image pair registration is the first step in InSAR signal processing, and its quality directly affects the quality of generated interference...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/30
Inventor 索志勇项红丽张金强李真芳
Owner XIDIAN UNIV
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