Vertical Accuracy Assessment of TanDEM-X DEM over Indian Test Areas

TanDEM-X mission has been acquiring data since 2010 to generate global DEM at 12 m spatial resolution with absolute height accuracy of 10 m and a relative height accuracy of 2 m. It is important to evaluate the accuracy of DEM generated from this data. This paper deals with the evaluation of TanDEM-X DEM using DGPS points over two test areas. The evaluation has been done with raw DEMs which are derived from single pair of data. On comparison with DGPS value, it is observed that TanDEM-X DEM has a RMSE value of 1.44 m for flat terrain, whereas it is 4.9 m for hilly terrain. When the DEM over hilly terrain test area is compared with ICESat data, we get an RMS error of 11.02 m. The effect of slope on DEM accuracy for this area shows that the error increases with slope as expected. A variation of 22.7 cm of height error per degree of slope is observed. DEM over barren land areas gives 6.64 m RMS error, and 17.7 m is observed in vegetation covered areas.