FREE GLOBAL DEM: CONVERTING DSM TO DTM AND ITS APPLICATIONS

Abstract. DTM is a digital model that visualizes height topography. DTM can be used for various survey mapping applications. DTM can be derived from DSM. Currently DSM is widely available but the availability of DTM is still rare, especially in Indonesia. In this study, DSM was obtained from a combination of DSM X SAR, SRTM, and TanDEM-X with the integration method. This DSM integration made height error correction and height reference field to the EGM 2008. This DSM integration has fulfilled the tolerance of vertical accuracy in 1.96σ (95%). This study aims to convert DSM to DTM and discuss some of the DTM applications. The study area of this study is Rote Islands (north and east side), especially in the Dead Sea Lake Area which includes Lake Oemasapoka to Oesu Island. DSM can be converted into DTM by considering several things, namely the canopy tilt angle to topography, the height of the vegetation approach, and the radius defined around the canopy. One way to get this parameter is to make contours on the vegetation in the DSM. After conversion of DSM to DTM, DTM is obtained at ground level. The DTM that has been produced needs to be done a height difference test and the making of longitudinal profile. This longitudinal profile will visualize the conditions of DSM and DTM so that the vegetation height will appear along the profile. The resulting DTM can be used for several applications such as topographic contours, watersheds, water levels, flow accumulation, slope, slope direction, and others.