Generation of Statewide DEMs and Orthoimages – Guidelines and Methodology
Cartosat-1 is a global, high resolution stereographic imaging mission to support enhanced applications in several areas of terrain mapping, natural resources management, disaster management, infrastructure and development planning. A collaborative project of generating statewide Digital Elevation Model (DEMs) and mosaic of Ortho-image for all the states and union territories in India has completed under the project namely Space based Information Support for Decentralized Planning (SIS-DP) using Photogrammetric techniques with Cartosat-1 stereo data.  Approximately 11000 stereo pairs of Cartosat-1 data were used in this process. Photogrammetric blocks for each state were processed using existing reference tiles and accordingly ortho-images were generated. The paper outlines the methodology for generating state-wide Digital Elevation Models (DEMs) and ortho-images. The guidelines that govern the quality of the output were discussed. Dissemination mechanism via public accessible web platform was described.