Impact of slope on DEM extracted from IRS 1C PAN stereo image covering Himalayan glaciated region: a few case studies

Abstract

Satellite stereo data is used for generating digital elevation models (DEM) and three-dimensional viewing of the terrain in a digital photogrammetric workstation. A good base to height ratio, usually greater than 0.5, is necessary for generation of good quality DEM. Processing of the stereo data requires a few GCPs, image matching between the pairing images and interpolation. Therefore these factors also control the accuracy of the DEM in addition to B/H ratio. The work described in this article highlights an additional parameter i.e. the terrain slope which plays an important role in DEM generation. To carry out this work, thirteen IRS 1C/1D PAN stereo pairs covering seven glaciated valleys and one non-glaciated mountainous region were processed. It was observed that broad glacier valleys with gentle slopes yield good matching than glaciers with narrow valleys and steep slopes. Higher B/H ratio with both the images having high tilt may result in poor image matching on high slopes. Good image matching is one of the important factors in governing the elevation accuracy of the DEM generated from satellite stereo images.