Interpretation of Radarsat-1 SAR Imagery of Riyadh for Mapping Applications

Abstract

A synthetic aperture radar (SAR) image obtained by the Canadian Radarsat-1 system and covering the City of Riyadh is evaluated for thematic accuracy levels required for planimetric mapping applications. After a brief account on the elements and factors affecting radar image interpretation, and the various parameters involved in these processes, a systematic approach was followed in interpreting the various elements that are likely to be shown on planimetric maps. Simple interpretational instruments were used to measure linear features and areas on the radar image. These were then compared with their map equivalents. The results showed that 80% of major roads can be interpreted with conviction; while only 30% of dry streams (wadi's) were discernible. Built-up areas could be interpreted to 85% accuracy and hills and raised ground to 70%. On the other hand, only 10-20% of vegetational areas were correctly identified. Combining these findings with the geometric testes carried out by the present author and other investigators, it seems that reasonable scale range obtainable from Radarsat-1 SAR image type, as tested in this experiment, will be 1/00000 to 1/500000. This is commensurate with the requirements of some basic thematic mapping applications such as forestry, hydrology, geography etc.