Radar synthetic phase unwrapping method based on branch-cut method and surface fitting

Abstract

The invention discloses a radar synthetic phase unwrapping method based on a branch-cut method and surface fitting. According to the main idea, the method comprises: conjugated multiplication of image data of an SAR image after image registration and image data of the SAR image after image registration is carried out to obtain an interferometric phase diagram and then obtain a pseudo association coefficient of the interferometric phase diagram; a pseudo association coefficient threshold value of the interferometric phase diagram is set to obtain a first quality area diagram and a second quality area diagram, and phase unwrapping is carried out on the first quality area diagram by using a branch-cut method to obtain an unwrapping phase of the first quality area diagram; fitting of the unwrapping phase of the interferometric phase diagram is carried out by using a polynomial surface fitting method to obtain a coefficient column vector of a polynomial fitting function of the interferometric phase diagram and an unwrapping phase curve surface with an error of the interferometric phase diagram; and the unwrapping phase curve surface with an error of the interferometric phase diagram is optimized by using a genetic algorithm, thereby obtaining an optimized unwrapping phase curve surface of the interferometric phase diagram. Therefore, the final unwrapping phase of the interferometric phase diagram is obtained.

Description

technical field [0001] The invention belongs to the field of interferometric synthetic aperture radar (InSAR) phase unwrapping, and further relates to a radar synthetic phase unwrapping method based on branch cutting method and surface fitting. Background technique [0002] Interferometric Synthetic Aperture Radar (InSAR) radar technology first generates two Synthetic Aperture Radar (SAR) images of the target, and then obtains a high-precision digital elevation map through image preprocessing and phase unwrapping. As a new type of space-to-earth observation technology, InSAR radar technology is the perfect combination of SAR radar technology and radio astronomy. It can not only accurately and efficiently identify the digital elevation map of the target, but also can work all-weather and all-weather. The above advantages This makes InSAR radar technology a new research hotspot in the 21st century. [0003] After SAR radar image registration, two single-look complex images (S...

AI Technical Summary

Problems solved by technology

The local method has fast unwrapping speed and high precision, but the unwrapping effect of this algorithm is poor in the area where the phase residual points of the interferometric phase image are densely distributed, or even unwrapped. The local method is represented by the BranchCut method , the algorithm uses the nearest neighbor principle to connect the phase residue points of the interferometric phase image to form branch tangent lines to isolate noise, and then integrate the difference phases of adjacent pixels of the interferometric phase image to realize phase unwrapping

[0005] However, because the branch cutting method only uses the phase residue information of the interferometric phase image, the branch cutting line using this algorithm will form a closed loop or the branch cutting line is placed in an improper position, resulting in the phenomenon of noise transmission.

The global method can also effectively unwrap the area where the phase residual points of the interferometric phase image are densely distributed, but the algorithm will transfer the unwrapping error to the non-noise area, resulting in a decrease in the accuracy of the phase unwrapping; and, the global method Represented by the least squares method, this algorithm uses the minimum mean square difference between the phase unwrapping gradient and the wrapping phase gradient to realize phase unwrapping, which can improve the accuracy of phase unwrapping and enhance stability, but the algorithm has a large amount of calculation and requires a lot of time to implement time

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