Method and system for orthorectification of high-resolution SAR (Synthetic Aperture Radar) image in fluctuating area

By generating simulated SAR images using high-resolution DEM observation parameters and combining them with a multimodal matching method based on geometric distortion perception, a geometric calibration model is constructed. This solves the problem of large geometric positioning errors in high-resolution SAR images in undulating and complex areas, achieves high-precision orthorectification, and reduces labor costs.

CN122049321APending Publication Date: 2026-05-15TONGJI UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
TONGJI UNIV
Filing Date
2025-12-23
Publication Date
2026-05-15

AI Technical Summary

Technical Problem

Existing high-resolution SAR imagery suffers from large geometric positioning errors and sparse control points in areas with complex undulations due to insufficient resolution of the digital elevation model (DEM), severe geometric distortion, and unstable multimodal matching, making high-precision orthorectification impossible.

Method used

By collecting observation parameters from a high-resolution DEM, simulated SAR images are generated and matched with real images to extract control points. Using a multimodal matching method based on geometric distortion perception, a geometric calibration model is constructed to correct positioning errors in the azimuth and range directions, thereby achieving high-precision orthorectification.

Benefits of technology

High-precision geometric positioning and orthorectification of SAR images were achieved in complex terrain, improving the reliability of matching simulated images with real images, effectively eliminating the interference of distorted areas such as shadows and overlaps on matching, and achieving precise geometric correction without ground control points, thus reducing labor costs.

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Abstract

The invention discloses an ortho-rectification method and system for a high-resolution SAR (Synthetic Aperture Radar) image in a fluctuating area. The method comprises the following steps: acquiring observation parameters of a high-resolution DEM (Digital Elevation Model); generating a simulated SAR image by using the observation parameters, matching the simulated SAR image with a real SAR image, correcting an initial positioning deviation, and extracting a control point of a fluctuating region by performing secondary matching on the corrected real SAR image; acquiring a high-density control point of a flat area in the optical reference image and the initially calibrated real SAR image by using a geometric distortion perception multi-mode matching method; and performing statistical analysis based on the control points of the flat area and the control points of the fluctuating area, constructing a geometric fine calibration model, and correcting positioning errors in the azimuth direction and the distance direction for the corrected SAR image to realize high-precision orthorectification. According to the SAR ortho-rectification method combining DEM simulation and multi-mode matching, the problems of fluctuation distortion, DEM low resolution and the like are solved under the condition of no GCP, and high-precision ortho-rectification is achieved.
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