On the Planimetric Accuracy Obtained from Synthetic Aperture Side-looking Radar Imagery

In this paper the experimental planimetric accuracy through performing geometric processing of three strips of Synthetic Aperture Side-looking Radar(SAR) imagery is reported,and the prospects for mapping medium and small scale maps are analyzed.The proposed method of solution has been procceeded in two stages,In the first stage,coordinates of the imagery of SAR are reduced to ground coordinates,they include the corrections of slant-to-ground rang reduction,along-track coordinates,relief displacements and earth curvature.Then,the reduced coordinates are transformed to geodetic coordinates with the help of a well distributed control points.The RMS errors in position at imagery scale computed from 158 check points are m_x=0.09mm m_y=0.08mm m_s=0.12mm The accuracy meets with the requirements of maps at a scale of 1:50000,also with ones of 1:25000 for remote areas.The results obtained herein are also tested by the author by using Derenyi and Leberl's high power polynomials.But the best one occures when the polynomials are limited to the second power without y₂ term.Hence the second power polynomial is taken to represent the law of radar systematic distortion.From the exprimental results and the theoretical analysis it is shown that the removal of the adverse effect of relief displacement can increase the accuracy remarkably.This is specially important for radar imagery.It is recommended that dividing the strip imagery into sections is a way to improve its accuracy.