Experiments on correction of geometric distortion of SPOT HRV image data based on a polynomial and ground control points indicate following features. In case of the Level-1A SPOT HRV image data the optimum degree of the polynomial is the 2-nd degree both for a latitude-longitude coordinate system and a plane rectangular coordinate system, while in case of the Level-1B data the optimum degree is the bilinear for the latitude-longitude coordinate system and linear for the plane rectangular coordinate system. A computer program for the correction of geometric distortion has been developed in which ground control points are not available. The result of the verification of the program in reference with well defined check points indicates that although an absolute error is large the standard deviation of the error is within 1 pixel for the multispectral mode data and within 2 pixels in case of the panchromatic mode data. The ground control points and check points utilized in the studies are those on the assumed standard height and are derived from the standard map published by Geographical Survey Institute of Japan, the satellite positions and the information of the geoid.
A method for Ground Contral Point, GCP acquisi-tion using simulated SAR image, derived from Digital Terrain Model, DTM, is proposed. The Japanese Earth Resources Satellite-1, JERS-1, will be launched in 1992. Before that it would be better to prepare GCPs for assessment of geometric accuracy of SAR imagery data. In order to acquire GCPs without real SAR imagery data, simulated SAR images were generated from DTM. In this study, simulated image is derived from elevation data only, under an assumption of a simple scattering model without consideration of complex dielectric constant of the targets of interest. The performance of the acquired GCPs was evaluated by using several measures with texture features of GCP chip images. This paper describes the details about proposed method for acquisition of GCPs and simulated results on relationship between texture features and GCP matching success rate corresponding to the crosscorrelation between reference and distorted GCP chip images.