Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Validation of Airborne Sensor Photogrammetric Digital Terrain and Global Digital Elevation Models around Mekelle City, Ethiopia

Version 1 : Received: 1 September 2020 / Approved: 2 September 2020 / Online: 2 September 2020 (08:30:48 CEST)

How to cite: Biryhane, H.; Bedada, T.B.; Gessesse, B.; Vermeer, M. Validation of Airborne Sensor Photogrammetric Digital Terrain and Global Digital Elevation Models around Mekelle City, Ethiopia. Preprints 2020, 2020090034 (doi: 10.20944/preprints202009.0034.v1). Biryhane, H.; Bedada, T.B.; Gessesse, B.; Vermeer, M. Validation of Airborne Sensor Photogrammetric Digital Terrain and Global Digital Elevation Models around Mekelle City, Ethiopia. Preprints 2020, 2020090034 (doi: 10.20944/preprints202009.0034.v1).

Abstract

The quality of photogrammetric-based derived products like orthophotos, digital terrain models (DTMs) and digital line maps as well as the global digital elevation models (DEM) are rigorously dependent on the accuracy of image orientation. This paper evaluates the vertical accuracy of aerial photogrammetric Digital Terrain Model (DTM), Shuttle Radar Topography Mission (SRTM), Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER), and TerraSAR-X's twin satellite of TanDEM-X (TDX) datasets against in-situ orthometric heights computed from ellipsoidal heights and the 2008 Earth Gravitational Model (EGM2008) derived geoid heights in Ethiopia. The quality of the four global digital elevation models was also validated against the aerial photogrammetric DTM measurements. Besides, the accuracies of the photogrammetric DTM and the four DEM products were checked for their compliance to the American Society for Photogrammetry and Remote Sensing (ASPRS) standards as well as the Ethiopian national vertical data evaluation standards. The study showed that the photogrammetric DTM is in a good agreement with the reference orthometric heights compared to SRTM, ASTER and TDX datasets. More precisely, the result has an absolute accuracy of 1.67 m at Linear Error (LE) 95% confidence level, while the absolute accuracy of SRTM3 arc seconds (SRTM3) at LE 90% (11.91 m) is better than its product specification (16 m). The absolute accuracy of SRTM1 arc second (SRTM1) (7.70 m at LE 90%) surpasses that of SRTM3, whereas the absolute accuracy of ASTER DEM is somehow below its product specification. TDX also has the same vertical accuracy (10.29 m at LE 90%) compared to its product specification (10 m). Furthermore, the vertical accuracy of the photogrammetric DTM meets the100 cm vertical accuracy of the 2015 ASPRS standard. However, it does not meet the Ethiopian national vertical data accuracy requirement standard, i.e., RMSEz of ± 0.45 m. In general, the photogrammetric DTM, SRTM1, and TDX have been proven a superior product over the SRTM3 and ASTER DEMs, and better to use these products for high-level precision and accuracy required applications.

Subject Areas

vertical accuracy; photogrammetric DTM; ASTER; SRTM; TanDEM-X; orthometric height; geoid height

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