Generation of Dtm from Stereo High Resolution Sensors

Digital terrain models (DTMs) were extracted from high-resolution stereo images (SPOT-5, EROS-A, IKONOS-II and QuickBird) using a three-dimensional universal physical model developed at the Canada Centre for Remote Sensing, Natural Resources Canada. DEMs were generated using an area-based multi-scale image matching method and then compared to 0.2-m accurate lidar elevation data. Elevation linear errors with 68% confidence level (LE68) of 5.5 m, 6.5 m, 20 m, 6.4 m and 6.7 m were achieved for SPOTHRS, SPOT-HRG (5 m), EROS, IKONOS and QuickBird, respectively. The poor results for EROS are mainly due to its asynchronous low orbit, which generated large geometric and radiometric differences. The best relative results are obtained with SPOT5. Since the SPOT, IKONOS and QuickBird DEMs were in fact digital surface models, where the height of land covers was included, elevation accuracy was performed only on bare surfaces (soils and lakes), where there was also no difference between the stereo-extracted elevations and thelidardata. LE68 of 2.7 m, 2.2 m, 1.5 m and 1.2 m were then obtained for SPOT-HRS, SPOT-HRG (5 m), IKONOS and QuickBird, respectively. Relatively sensor resolution, multi-date across-track SPOT, with also a smaller B/H of 0.77, achieved three to four times better results than same-date in-track IKONOS and QuickBird with B/H of one: half-pixel versus 1.5 or two pixels.