Investigations on the Relation of Geomorphological Parameters to DEM Accuracy

H. Papasaika, E. Baltsavias
Institute of Geodesy and Photogrammetry
ETH Zurich
Wolfgang-Pauli-Str. 15, CH-8093, Zurich, Switzerland
Telephone: +41 44 6336808
Email:(haris, manos)@geod.baug.ethz.ch

In recent years, collection and processing techniques for Digital Elevation Models (DEMs) generation have improved rapidly, providing DEMs with higher resolution and accuracy. Each DEM contains errors due to the primary data acquisition technology and subsequent processing software, the surface relief and landcover (Li 1992). Parameters such as elevation, aspect, slope, vertical curvature and tangential curvature are useful to identify and describe geomorphological characteristics. Preliminary research studies have partially addressed the correlation between DEM accuracy and terrain relief (Toutin 2002, Crosetto and Crippa 2000). The morphology of the terrain and the sampling density used can have a significant influence on the accuracy of the DEM (Li 1992, Gao 1995, Gao 1997, Weng 2002). Some geomorphological parameters, such as average terrain slope, seem to be positively correlated with the decrease in accuracy of the DEM (Felicísimo 1992).

Our work is embedded within the EU FP6 project Pegase (Pegase, 2009), which aims at the development of an autonomous landing and take-off system for aircrafts. This system should use geodata on-board of each aircraft and DEMs are a crucial part of this geodata. To generate higher quality products covering all airports worldwide, DEM fusion is needed. DEM (and generally data) fusion needs first a quality characterisation of each input. Unfortunately, almost all available DEMs come with one global accuracy measure, which does not represent correctly the local accuracy variations. Thus, we try to exploit various parameters that influence the DEM accuracy, in order to assign to the DEM locally (ideally for each DEM point) a quality factor. The parameters that influence DEM accuracy are many, including geomorphology, landcover, DEM generation technology etc. with interrelations among them. In this paper, we report on investigations regarding the relation of some geomorphological parameters to the accuracy of DEMs. As DEMs, we mean both Digital Terrain Models (DTMs) and Digital Surface Models (DSMs). Till now, we have worked mostly on DSM fusion. Although Pegase relates to airports, the DEM fusion process should be applicable to any dataset. After developing the basic methodology, a test, using various DEMs at a site with varying terrain relief and landcover, was conducted and discussed here.

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