Geometric Accuracy Evaluation of the DEM Generated by the Russian TK-350 Stereo Scenes Using the SRTM X- and C-band Interferometric DEMs

TK-350 stereo-scenes covering 200 km μ 300 km on the ground with a base-to-height-ratio of 0.52 have been analysed on Zonguldak testfield in the northwest of Turkey. The pixel size on the ground is 10 m. Control points digitised from 1:25 000 scale topographic maps have been used in the test. The sensor orientation was executed by the PCI Geomatica®V8.2 software package. TK-350 stereo-images can yield 3D geopositioning to an accuracy of about 10 m horizontally and 17 m vertically. Based on this orientation, DEM with 40 m cell size was generated by the related module of PCI system. For the validation of extracted DEM, matched data was checked against the interferometric DEMs from SRTM X- and C-band SAR data. Based on this comparison, the RMSE of Z values was found to be in the range of 25.6 to 36.9 m and 28.7 to 38.7 m outside and inside the forest area, respectively. However, accuracy results obtained against the SRTM C-band DEM are more representative than those of X-band since the coverage of C-band DEM on the interest area is larger than the X-band. There are some systematic shifts of the TK-350 DEM against the SRTM DEMs which lie between the 3.7 m to 6.2 m which is probably due to the different sensor orientation of TK-350 and SRTM datasets. Height discrepancies are also analysed as a function of terrain slope. It was found that slope depending components were always larger in the case of C-band DEM because of its larger cell spacing. In the forest areas, more dependency upon the slope was observed against the open areas.