RPC model correction coefficient acquisition method
An acquisition method and model correction technology, applied in the field of radar, can solve problems such as affecting positioning accuracy, large deviation, and inaccurate RPC coefficients, and achieve the effects of improving accuracy, ensuring stability, and avoiding too large a normal matrix condition number.
Active Publication Date: 2015-10-14
BEIHANG UNIV
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Problems solved by technology
The RPC coefficients solved at this time are not accurate enough, which leads to a large deviation between the correction result and the actual position when the RPC model is used for geometric correction, which seriously affects the positioning accuracy
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[0056] A kind of RPC model correction coefficient calculation method of the present invention, specific embodiment is:
[0057] Step 1. Write out the RPC model coefficient solution matrix according to the mapping model:
[0058] (a) Create a spatial grid. Simulation scenarios such as figure 2 The height of the aircraft shown is 500Km, the pitch angle is 45°, the scene size is 4000m×6000m, the azimuth resolution is 1m, and the range resolution is 1.5m. Grid, each network point is evenly distributed on the image, and then a three-dimensional object grid is established by spatial layering. The grid covers the spatial range of the three-dimensional terrain surface, and the number of elevation layers is 11.
[0059] (b) Get control points. According to the rigorous imaging model, the corresponding image point coordinates are calculated for each network point in the corresponding spatial grid. At this time, there are N=1331 control points, and each grid point (b i , l i , h ...
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The present invention discloses a RPC model correction coefficient acquisition method, comprising steps of: step 1, acquiring a RPC model coefficient solving matrix according to a mapping model and control point information; step 2, performing a ridge estimation based on a L curve; step 3, performing an iterative calculation of a spectrum correction on a ridge estimation solution based on the L curve, iterating the fixed times of iteration, and selecting a most accurate solution as a RPC model coefficient solution; According to the present invention, a biased estimation based on the L curve-ridge estimation is used to solve an initial coefficient solution, thereby avoiding a too large condition number of a matrix while using a least squares method to solve, and avoiding defects in an obtained solution offset truth value caused by serious illness of a coefficient matrix, and ensuring the stability of a coefficient solution; According to the present invention, after a ridge estimation based on a L curve is used, a spectrum correction iteration is performed on an obtained coefficient solution that is used as an initial iteration value, and an appropriate initial value can greatly reduce the number of iteration, and effectively improve the accuracy of the coefficient solution, not only promote the speed of solving, but also ensure the precision of an solution.
Description
technical field [0001] The present invention relates to the field of radar technology, in particular to a method for calculating RPC (rational polynomial coefficient) model coefficients for geometric correction of synthetic aperture radar (SAR) slant-range images. Background technique [0002] The RPC model is a general geometric model of satellite remote sensing images. It is a generalized sensor model obtained by fitting the strict imaging geometric model based on making full use of auxiliary parameters attached to satellite remote sensing images. The theory of the rational function model appeared very early, but when it was first proposed, there were not many related studies because it was rarely used in the field of photogrammetry and remote sensing. After the launch of the IKONOS satellite, the RPC model received more and more attention. s concern. The International Photogrammetry and Remote Sensing Association has established a special working group to study the accur...
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IPC IPC(8): G06T17/00G06T7/00
Inventor 孙兵张新良张洁琼张施雨
Owner BEIHANG UNIV