Performance of Large Area Covering Height Models

Digital height models (DHM) are a basic requirement for several applications. The generation of DHM is time consuming and expensive, but several large area covering height models are available free of charge or commercially. For practical use it is important to have some information about the quality, as accuracy, accuracy characteristics, areas with problems, height definition as digital surface model (DSM) or digital terrain model (DTM) with heights of the bare ground, resolution (point spacing), homogeneity and availability. The free of charge available height model from the SRTM mission is well known and dominating up to now. It has been improved to different versions as by gap filling and spike removal and different products by merging with other data as in case of the ACE2 corrected by radar altimeter data. The point spacing of 3 arcsec has been improved by merging with the also free available ASTER GDEM2 to the commercial NEXTMap World 30 with 1 arcsec point spacing. ASTER GDEM2 has some problems with homogeneity caused by varying number of images used for the individual heights; nevertheless it is better as the GMTED2010 with 7.5 arcsec spacing, which replaced the GTOPO30. ETOPO1 is just limited to 1 arcmin point spacing. For 2016 ALOSworld DEM, using all usable ALOS/PRISM images, is announced with 5m spacing, which may change the situation. Commercial height models as Elevation 30 based on SPOT 5-HRS, NEXTMap determined by airborne InSAR, Euro-MAPS 3D, based on Cartosat-1 and WorldDEM based on TanDEM-X have advantages in point spacing and accuracy. WorldDEM seems to dominate the commercial versions in future. The characteristics and accuracy of the different height models are described to allow a selection corresponding to the individual requirements.