DEMs Created from Airborne IFSAR – An Update

The factors affecting the wide-scale use of DEMs (Digital Elevation Models) and their associated ORRIs (Ortho-Rectified Radar Images) created from airborne IFSAR (Interferometric Synthetic Aperture Radar) have been evolving rapidly over the past few years. These factors include both technical and non-technical characteristics. In this paper we review several of these characteristics including vertical accuracy, sample spacing, image resolution, bald-earth extraction, vegetation penetration, cost and availability. These factors will be reviewed mainly in the context of the STAR-3i and TopoSAR systems, which are both commercial airborne IFSARs operated by Intermap Technologies. The objective is to provide a status report on what can be expected with current data sets and what might be expected in the near future. Key to an understanding of most of these factors is an appreciation of price vs. performance and how DEMs derived from airborne IFSAR relate to those created from satellite systems on the one hand and lidar or photogrammetric systems on the other. In particular we will focus on two major ‘events’ that illustrate what can now be considered status quo, on the one hand, and what is a very interesting developmental trend on the other.