Research On The Method Of Geometric Processing For Airborne SAR Data Based On POS Data

Synthetic Aperture Radar (SAR) is an active sensor, and it can penetrate the fog and cloud. So it can be used to complete the data acquisition task in the special area where the optical sensor can't get eligible image. However, because SAR is slant range imaging, there is geometric distortion in the near and far range of the image, and there is large geometric distortion caused by the terrain, such as overlapping cover, shrinkage and other geometric distortion, especially in the mountain areas. So it prevents us to extract information and make full use of SAR images. Therefore, there is important theoretical and practical value about the SAR geometric process method in this paper.This article is based on " The project of West China topographic mapping at 1:50,000 scale ". And in response to the issues such inherent features of SAR image and the difficulty in obtaining ground control points in complex terrain, this paper put forward a set of method about SAR image rectification and geocoding based on POS/PPP technical and using sparse control points. The main content are as follows:(1) The development survey, work principle and the application in supporting photogrammetry of the INS/GPS integrated navigation system and DGPS and PPP approach and their respective advantage will be introduced in this paper, compare the accuracy of the two cases to analyze the accuracy of PPP approach whether meets the precision requirements of geometric correction of Airborne SAR, So this paper put forward to the based on the POS date and PPP processing method Airborne SAR geometry process.(2)With analysis of the original indirect method of geometric correction, combined with characteristics of Airborne SAR, we put forward indirect method based on systemic error correction. The systemic error correction of Airborne SAR is added to the indirect model to remove the indirect geometric model error from systemic error. And the slant range measurement error correction and time delay correction are added to the direct method to increase the precise of orientation. And the methods are validated by a lot of experiment.(3)Because the bandwidth is narrow and the mount of images is large in Airborne SAR, the amount of work is heavy. To reduce the amount of work, this paper analyzes the case of different number of control points for geometric correction can meet the precision requirements of 1:50000 relief map. And to find the optimization scheme, that is based on two or three GCPs orientation method for achieve the aim of geometric process based of sparse control points.(4)To meet the need of production of DOM and DOM in the project of West China topographic mapping at 1:50,000 scale, this paper used the ahead methods to make experiment of production of DOM and DOM to verify the feasibility of the methods.In addition, by use of Visual C++ 6.0 development platform, corresponding software modules have been founded on the basis of the independent developed software"ImageInfo-SAR workstation", thus providing technical and software support for the successful completion of the West mapping mission.