Dem Generation from High Resolution Multi-view Data Product

High resolution space-borne remote sensing image data show a high level of detail and provide many opportunities to be integrated into remote sensing applications. In particular, surface mapping from multi-view and stereo data sets becomes feasible with height accuracy in the meter range. Cartosat-1 and Cartosat-2 are the two Indian satellites which provide the high resolution images. Cartosat-1 is a unique satellite having along track stereo imaging capability with 2.5 m resolution. Cartosat-2 is the second satellite in the Cartosat series which was launched during January 2007 by PSLV. Cartosat-2 is a high agility advanced satellite with a high spatial resolution of better than 1m in panchromatic band with an operational life of 5 years. Cartosat-2 provides standard multiple scene product called as Multi-view with an overlap of more than 80 percent. Stereo image viewing has been the most common method of elevation modelling used by the mapping, photogrammetry, and remote sensing communities. Multi-view Image contains radiometrically corrected images with rational polynomial coefficients. Maximum three multi-view images are possible in a single pass of the satellite. In this study Multi-view Images have been treated as stereo image pairs to obtain stereoscopy. Generating DEMs from stereo data normally requires the use of a geometric model and ground control points (GCPs). The collection of GCPs presents a significant problem in many practical applications due to non availability of GCPs. A DEM generation method which requires no GCPs would therefore be of significant interest to users of stereo data. The RPC model was computed for each image. A pair of quasi-epipolar image is generated from the stereo images to retain elevation parallax in the X-direction. An automated image matching procedure is then used to produce the DEM. In this study, automatic DEM extraction of Cartosat-2 multi-View data without the use of GCPs has been evaluated, as well as the improvement of extracted DEM quality by applying horizontal shift on reference DEMs from the available Global DEMs or other source DEMs. High quality DEM has been generated at 2 m grid spacing which will be of immense use for producing digital city model (DCMs).