Digital Elevation Quality Derived from Medium-Format Digital Cameras

Medium-format digital cameras are a useful tool in airborne lidar missions to produce digital ortho-images. This study investigates the quality of digital elevation models (DEMs) and digital surface models (DSMs) derived from such cameras. An image-matching strategy is used to produce height information from highly overlapping images and the quality of the derived height information is analysed using synchronous lidar point clouds as the reference data. The evaluation focused on various types of land cover and DEM generation methods. The RMSE between lidar and image-derived height information for two datasets was 0·054% and 0·027% of the flying height in flat, bare-earth areas, but studies with manually edited vegetated areas using stereo photogrammetry revealed high uncertainties, especially in steep terrain.