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Space-borne Interferometric SAR for digital elevation model in the tropical region: An initial result of Sentinel-1 RADAR data over the Indonesian archipelago

Despite the fact that the Sentinel-1 satellites was designed for surface deformation monitoring, researchers have been able to produce digital elevation model (DEM) using repeat-pass Interferometry. It is, however, mostly conducted in the subtropical zone and the temperate zone. Only a couple of publications were found conducted in the tropical region. Highly dense vegetation in tropical region could cause temporal decorrelation when repeat-pass Interferometry is used. However, the vegetation cover, as well as landcover condition, is still varied within this region. Therefore, our main objective is to identify the suitable area for a successful DEM extraction using Sentinel-1 repeat-pass Interferometry in the tropical region. This paper presents our initial results on the repeat-pass Interferometry using Sentinel-1 data Indonesia. Thirty-two (32) interferometric pairs were chosen over two areas of interest (AOI). The pairs were chosen with different temporal and perpendicular baselines. Both AOI is located in South Sulawesi Province, Indonesia. The AOI has different climate conditions. The produced DEMs were visually inspected, and the best results were compared to ICESat-2 and DEMNAS datasets. The Root mean square error (RMSE) was calculated on 5368 sample points. Our initial results show that only AOI_2, with its relatively arid environment, can produce meaningful DEM. Finally, a pair with six days difference and 136-meter perpendicular baseline came out with the best results. Compared to ICESat-2 ATL08 and DEMNAS data, the RMSE produced was 33.92 and 35.13 meters, respectively. Our next task is to maximize the accuracy by tweaking several parameters, as well as identifying the same climatic and/or landcover conditions found on this paper throughout Indonesia and the whole tropical region.