Performance Evaluation of Urban Canopy Parameters Derived from VHR Optical Stereo data

Urban Canopy Parameters (UCPs) are parameters, which are utilised to define thermal, radiative and roughness properties of urban areas, having significant impact on urban microclimate. The rapidly growing urbanization especially in developing region leads to modification in urban geometry, which calls for characterization of UCPs in the countries of such region to account for high population pressure, heterogeneous urban environment and subsequent impacts on global climate change. A research study conducted in Delhi, India found that Very High Resolution (VHR) optical satellite stereo datasets provide reasonable accuracy with respect to extraction of building height and footprints, which is further employed for computation of UCPs. However, the study evaluates only the key input parameters due to non- availability of 3D geodatabase. Hence, in this study an attempt has been made to evaluate all UCPs derived from VHR optical stereo along with key input parameters against reference data collected from field in the city of Bhubaneshwar, India. Performance evaluation with reference data derived UCPs shows that all the UCPs retrieved from VHR Optical Stereo data has high prediction accuracy. Overall bias, overall Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) from satellite derived UCPs was found to be better than 1m for most of the UCPs except for Building Surface Area to Plan Area Ratio, Height-to-width Ratio, and Complete Aspect Ratio which is found to be less than 2.7m. The correlation coefficient value were also observed to be more than 0.7 for most of the UCPs except Plan Area Density , Roughness Length and Frontal Area Density. The study concludes that UCPs derived from VHR Optical Stereo data has high accuracy even in the low -to-medium rise urban environment of study area. The study has high potential to be replicated in countries of developing region, which has similar development characteristics, and face resource and policy constraints with respect to availability of Airborne LiDAR and SAR data.