Principles of Modern Radar - Volume 2 1891121537

8.2 Digital Terrain Models 343FIGURE 8-2Comparison of twoDEMs of a 2 × 2kmarea of Eichenau(close to Munich,Germany) derivedfrom different DTEDdata levels.(a) Derived fromDTED level 2 SRTMdata. (b) Derivedfrom DTED level3 E-SAR data.(Courtesy of GermanAerospace Center(DLR).)(a)(b)(a)FIGURE 8-3 Comparison of two DEMs of the Park City, Utah area. (a) DTED level 2 DEMfrom the U.S. Geological Survey. (b) DTED level 4 DEM from the Sandia RTV InSAR.(Courtesy of Sandia National Laboratories.)(b)increasing level of detail associated with increasing DTED levels [6-8]. The Shuttle RadarTopography Mission (SRTM) conducted in 2000 collected data from low Earth orbit intendedto support mapping of 80% of the earth’s surface at DTED level 2 [9,10]. The U.S.Army’s Rapid Terrain Visualization (RTV) demonstration developed an airborne systemfor near real-time generation of DTED Level 3 and 4 products over localized areas [7]. Todate, DTED level 5 data typically requires use of an airborne LIDAR system. Figure 8-2compares a small portion of a DEM of the same area rendered at DTED level 2 derivedfrom SRTM data (Figure 8-2a) with a DTED level 3 rendering, derived from E-SAR data(Figure 8-2b). i Figure 8-3 is another example comparing a U.S. Geological Survey DTEDlevel 2 DEM of the Park City, Utah area to a DTED level 4 DEM based on data collectedby the RTV InSAR system.i E-SAR is the “experimental SAR” developed by the German Aerospace Center (DLR). Seehttp://www.op.dlr.de/ne-hf/projects/ESAR/esar englisch.html.