Application of SAR Interferometry on DEM Generation of the Grove Mountains

The Grove Mountains Area is situated to the southwest of Princess Elizabeth Land, the inland areas of east Antarctica. Adopting Landsat-4 TM images, a coloured satellite image map of Grove Mountains was produced and used to design an expedition route to Grove Mountains in 1998. In 2000, a field survey of the core area was completed with GPS and total station surveys. However, traditional mapping methods are no longer the most efficient means of obtaining topographic maps or DEM in large areas, especially those areas that are more inaccessible. Synthetic aperture radar interferometry has been proposed as a potential technique for digital elevation model (DEM) generation, topographic mapping, and surface motion detection. This paper presents an experimental investigation of the ERS-1/2 SAR tandem data on DEM generation of the Grove Mountains Core Area, and compares the DEM derived by INSAR with the DEM generated using field survey data. The paper confirms that INSAR is a very valuable technique to be utilized in Antarctica, and that INSAR can be employed to produce complementary field survey products. Introduction Up until the mid-1980’s, maps of Antarctica’s interior remained largely incomplete containing a great deal of white, unmapped space. Satellites using visible light had produced detailed surface images, but their angles of view excluded more than 3.1 million square kilometers pole-ward of about 82° south latitude. Then in 1997, the Canadian RADARSAT-1 satellite was launched into orbit. With its synthetic aperture radar (SAR) antenna looking south towards Antarctica, it permitted the first high-resolution mapping of the entire continent of Antarctica. In other areas of Antarctica, digital elevation models (DEM) and topographic mapping had been obtained by different means, such as synthetic aperture radar, radar altimeter, laser altimeter, radar echo sounding, GPS surveys, aerial photographs, and geodetic maps. In 1998, China planned an expedition to the Grove Mountains Area, located to the southwest of Princess Elizabeth Land, inland areas of east Antarctica (see Figure 1) for the first time. Adopting Landsat-4 TM images, the Chinese Antarctic Center of Surveying and Mapping (CACSM) completed a colored, satellite image map of the Grove Mountains at a scale of 1:100 000 in August 1998 to prepare the expedition route and navigation to Grove Mountains Area during the 15th CHINARE 1998/1999. The topographical map of the core area (see Figure 2) was printed after the GPS total station field survey was completed. Application of SAR Interferometry on DEM Generation of the Grove Mountains Dongchen E, Chunxia Zhou, and Mingsheng Liao However, in Antarctica, traditional mapping methods are no longer the most efficient means of obtaining topographical maps or DEM in large areas especially in inaccessible or difficult environments. Synthetic aperture radar interferometry has been proposed as a potential technique for DEM generation, topographic mapping, and surface motion detection, especially in inaccessible areas. Using the Grove Mountains core area, a case study for DEM generation was completed. In this paper, the preliminary experimental results based on ERS-1/2 tandem data are presented. Further, with the hard-won field survey data, comparison and analysis of DEM derived by tandem radar image data with DEM generated with the topographic points is carried out. Methodology The tandem operation of ERS-1 and ERS-2 satellites, with a short temporal baseline, gives a better time correlation for the DEM generation. It utilizes the two single-look complex images of the same area to form an interferogram and generate threedimensional information. The principle used to obtain height h is illustrated in Figure 3. With reference to the geometry, the height h of a ground point can be given by: h H R1 cos H cos , (1) where H is the flying height, R1 and R2 are the distances between the scatters and the radar antennae O1 and O2, respectively; is the look angle, B is the baseline, and is the baseline tilt angle. Meanwhile, interferometric phase difference can be expressed as 4 (R2 R1), where is the wavelength, and if R R2 R1, then,