Assimilation of DEMs Generated from Optical Stereo and InSAR Pair through Data Fusion

Abstract

Main objective of this study is to compare and assimilate the digital elevation models (DEMs) generated using C-band Envisat, L-band ALOS PALSAR Interferometric SAR (InSAR) datasets and Cartosat-1 optical stereo data. The study area is Dehradun city and surroundings including lower Shivalik hills i.e. the younger Himalayas in the south and higher Himalayas on the north. The general elevation of the area ranges from 400m to 2000m AMSL. Ground control points (GCPs) collected from Differential Global Positioning System (DGPS) survey, were used for satellite triangulation of optical data & geocoding of InSAR data. RMSE for satellite triangulation for cartosat-1 is 0.745 using 6 ground control points and 3 check points. It is found that when GCP’s are used along with reference DEM (SRTM), the DSM generated by ALOS PALSAR and DSM generated from Cartosat-1 stereo data are well representing the terrain. The fusion of imagery from multiple sensors has been in use in remote sensing for scientific exploration in the past but there is a little work done on data fusion application for generation of topography (DEM) through Optical stereo and SAR interferometry data sources. The defined framework for data fusion uses three fundamental steps in the analysis of the system namely, identification, estimation, and validation for algorithm preparation. The knowledge of the study area, i.e. the field, and the processes involved in the DEM generation of optical and InSAR data are cognitively used for rule-based decision making in the algorithm for mathematical generation of resultant DEM through data fusion implemented at feature level.