Orthorectification method of non-control satellite-borne SAR (synthetic aperture radar) image based on inverted RD positioning model

Abstract

The invention provides an orthorectification method of a non-control satellite-borne SAR (synthetic aperture radar) image based on an inverted RD positioning model. By the method, the problem that ground height values need to be iteratively acquired in the prior art can be solved; the orthorectification process of the SAR image is easy for multiple programming; and the processing efficiency is improved on the basis of ensuring the geometric correction precision. The method comprises the following steps of firstly constructing a slant distance doppler equation set to obtain geography latitude and longitude of four points by using satellite orbit positions corresponding to pixels; then mapping a map to obtain the east coordinate and north coordinate of the four points and the needed image map range; mapping an inverse map to obtain the geography latitudes and longitudes of the pixels; converting into position vectors of the pixels under a ground-fixed coordinate system; finally resampling gray values of the needed image pixels by using a bilinear interpolation method; and obtaining the corresponding gray values until all pixels in the needed image map range are calculated, thereby obtaining the corrected image.

Description

technical field [0001] The invention relates to an orthorectification method for an uncontrolled spaceborne SAR image based on an inverse RD positioning model, and relates to the fields of synthetic aperture radar (SAR) image processing and image geometry correction processing. Background technique [0002] With the successful launch of high-resolution new SAR sensor satellites (such as TerraSAR-X, RadarSAT-2, etc.), their role in national economic construction has become more and more prominent. However, due to the special slant-range imaging mechanism of SAR, the geometric distortion caused by terrain fluctuations is large, and the positioning error is serious, which leads to difficulties in quantitative geometric analysis and image interpretation, which largely limits its application in surveying and mapping, forestry, and geological disasters. applications in the field of prevention. Therefore, there is a wide range of application requirements and great technical diffic...

AI Technical Summary

Problems solved by technology

[0011] 1. Empirical formulas are needed to simulate SAR scattering characteristics, but empirical formulas lack universality and are difficult to use in engineering mass production;

[0012] 2. Using DEM data to simulate SAR images can only adapt to mountainous areas with severe terrain fluctuations. For spaceborne SAR images with a wide coverage area that has both flat areas and complex terrain fluctuations, the positioning accuracy after correction is poor

[0014] 1. It is difficult to perform parallel programming in the iterative solution process, and the operation efficiency is low;

[0015] 2. In order to reduce the amount of calculation, the points in the grid are replaced by polynomial models, which do not conform to the strict geometric model of SAR, and the geometric distortion is relatively large after correction

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