RADARSAT and IFSARE: complementary SAR sources for DEMs

Technology has recently become available that enables users to obtain high quality Digital Elevation Models (DEMs) almost anywhere in the world and with delivery times that are much shorter than the mapping industry normally experiences. This new capability is timely because DEMs are being used increasingly in a host of applications ranging from GIS-based topographic data bases to tower-siting in the telecommunications industry. Synthetic Aperture Radar (SAR), because of its cloud-penetrating capability, allows data acquisition in large parts of the tropics where imaging with conventional optical systems has previously been problematic and expensive. In this paper we describe two solutions that are being offered by Intermap Technologies Ltd. Using RADARSAT stereo, DEMs can be created at levels of detail appropriate to 1:100,000 or possibly 1:50,000 mapping scales. This can be done over wide areas, quickly and at low cost. On the other hand, IFSARE, an interferometric SAR carried aboard a LearJet, creates DEMs of much greater detail, with sample spacing of 5 meters or less and vertical accuracy tested to less than 2 meters. This is appropriate to mapping scales of 1:10,000 or better. The solution selected for any particular application depends on the scale or level of detail that is needed and the nature of the application. A description is given of these two complementary systems, including specifications, test results and visual examples. Some comments are included with respect to cost versus detail of the associated products.