Uncovering the statistical and spatial characteristics of fine toposcale DEM error

The aim of our study was to characterize statistical and spatial details of the errors in a fine toposcale DEM derived by contour data. The fine toposcale DEMs are typically represented in a 5 - 50m grid and used in the application scale 1: 10 000 - 1: 50 000. The errors were determined by using high-quality reference data covering the entire study area from an airborne laser scanner. The work was motivated because of the essential role played by the correct characterization of DEM error in error-propagation studies. The results showed that the spatial autocorrelation of the fine toposcale DEM error was the result of a complex combination of random and systematic-like components, and its appropriate modelling by geostatistical methods is problematic because of the small extent of the areas in which the assumption of stationarity is valid. In addition, describing the shape of the DEM error distribution was impossible with a single parameter of dispersion. This was due to a large number of outliers, which suggests that more robust descriptors of the error should be used in addition to conventional error statistics.