The DEM generation of a volcano using airborne SAR interferometry

The airborne interferometric SAR technique enables us to generate a digital elevation model (DEM). However, in the mountainous area with steep terrain, we cannot obtain some DEM data because of radar shadowing, layover, etc. To generate the complete DEM of the observed area, it is necessary to observe with different incident angles and directions, and compound some DEMs obtained from the data of different incident angles and directions. In addition, if we use a light airplane, which is much affected by turbulence, the generated DEM contains large height errors caused by the intense body motion. Therefore, in case of the map projection, location errors are caused. As a result, it is very difficult to compound the DEM with accuracy. The volcanic eruption of Miyake Island in Japan occurred in July 2000, caused large-scale cave-in. We observed the crater by airborne interferometric SAR with two different incident angles from four directions in order to generate the DEM of the inside of the crater. After data acquisition, we tried to improve the accuracy of the DEM. The method is to iterate the following process, namely motion compensation considered to the rough target height in the azimuth compression in time domain and the interferometric SAR processing. Then, we were able to generate a comparatively accurate DEM, which covers the whole of Miyake Island with the inside height information of the crater.