Abstract: In an attempt to improve the global accuracy and reliability of the transformation from 2D coordinates of GB-SAR images to local 3D coordinates, and to overcome the limitation of traditional similarity transformation parameter estimation method, we propose to employ 3D laser scanning data to assisting the transformation of GB-SAR image coordinates. Firstly we derive the formula for calculating the scaling factor of the similarity transformation parameter estimation method. Analysis results suggest that the similarity transformation method is only applicable to local areas far away from radar and small in range with no dramatic change of height relative to the radar center because the calculation precision is not uniform for targets with varying relative height. We propose to provide external elevation information by 3D laser scanning technology, and subsequently transform GB-SAR image coordinates to local 3D coordinates by matching of point clouds and pixels on projection plane according to the geometric projection principle of GB-SAR imaging. Finally, we verified the effectiveness of the method of transforming GB-SAR by deformation monitoring experiment on the high slope of Geheyan dam. The research result is conducive to the 3D interpretation and analysis of GB-SAR deformation monitoring.

Key words: GB-SAR image, interference measurement, 3D laser scanning, coordinate transformation, scaling factor