ASSESSMENT OF STEREO-EXTRACTED DSM FROM WORLDVIEW-3 OVER DIFFERENT LAND COVERS DEPENDING ON THE IMAGING GEOMETRY
Keywords: DSM, WorldView-3, semiglobal matching (SGM), geometric accuracy, plastic greenhouses, completeness
Abstract. WorldView-3's 0.31m resolution in panchromatic mode, makes it one of the highest resolution commercial satellite in the world. This fact, together with its excellent stereo capabilities, make this satellite ideal for digital surface model (DSM) extraction working on very complex morphologies where a higher level of detail is required. In this communication we assess the quality (both completeness and vertical accuracy) of DSM extracted from WorldView-3 stereo pairs depending on the image geometry and sun position. Three different land covers (bare soil, urban areas and agricultural plastic greenhouses) have been tested in the Southeast of Spain (Almería). The well-known semiglobal matching (SGM) algorithm was used for all the extracted DSM. A clear relationship between DSM completeness and the WorldView-3 stereo pair imaging geometry measured as convergence angle was found. The completeness values decreased as convergence angles increased, especially in complex reliefs. In fact, convergence angles lower than 16 degrees is recommended when working on urban or greenhouse land covers. Moreover, sun light can cause glint effect in greenhouse areas. In this land cover, the attained results suggest to use stereo pairs taken when the sun presented a very low elevation. In Almería, the last happens in winter. The best results in all the tested land covers can be obtained by fusing DSM extracted from more than one stereo pair.