Geometric Quality Assessment of Vhr Satellite Imagery with Ortho-rectified Cartosat-1 Data – a Case Study

Data products from satellite instruments with moderate to high spatial resolution are assessed for their geometric accuracy with the help of topographic maps or geo-coded satellite imagery generally at 1:50,000 scale. With advancement in high precision attitude and orbital control systems onboard, considerable attention has been paid in the recent past to improve methods for better accurate assessment of geometric quality, especially for Very High Resolution (VHR) satellite imagery. These products are in general evaluated with the help of dense ground control points (GCPs) acquired through ground survey. But this survey is very expensive, and is difficult to perform in certain terrain conditions. In this paper, we propose to use ortho-rectified and mosaicked data from recently launched IRSCARTOSAT-1 in terms of both getting sufficient number of control points and their accuracy for assessment. Orthorectified products supplied after single strip triangulation algorithm with limited number of GCPs have been found to yield quite accurate in terms of location accuracy and internal distortion. In this paper, we suggest to use the mosaicked ortho-rectified data as reference map for geometric quality assessment of VHR (Cartosat-1) geo-referenced (standard) imagery and IRS-Resourcesat-1 LISS-4 MS image as well.