# The Influence of the Quality of Digital Elevation Data on the Modelling of Terrain Vehicle Movement
###### Abstract  
This study investigated digital terrain models and options for their evaluation and effective usage. The most important result of this study was the introduction of the slope reduction method for low-detail elevation models. It enabled accurate results of passability analyses by performing adjustments of slopes. In addition, the goal was to determine the strengths and weaknesses of selected data for use in cross-country mobility analyses, followed by recommendations on how to use these databases efficiently to obtain accurate results. The selection of elevation databases (1 m, 5 m, 10 m, 30 m) was determined by the focus of data development projects of NATO and current scientific research projects of the Ministry of Defence of the Czech Republic. Key findings showed potential for use in practise for all tested elevation models. Efficient usage of low-detail models in CCM analyses is limited; nevertheless, they can be augmented with additional vector data or automated remote-sensing technologies. DEMs; cross-country mobility; slope analysis; terrain vehicles; geospatial support in NATO +
Footnote †: journal: _Applied_  
the influence of soils and the quality of terrain surfaces. Values of slopes and results of cross-country movement (CCM) analysis were compared for each terrain model in selected areas. The key approach of the article, i.e., identifying the influence of slope accuracy on the results of CCM analyses, was based on both national and international studies. The basic methodology of analysis of elevation models was given in [4]. The study compared the accuracy of heights of terrain models with measured values in the field and assigned them specific output statistics. These statistics showed the specific advantage of 5 m \(\times\) 5 m DEMs. It combined both assets in terrain detail and data availability across the world that are needed for practical use, such as visibility or passability analysis. Despite some problems with accuracy, especially in areas of significant microrelief shapes, DEMs comply with the declared accuracy and they are a major contribution to the field of geoinformatics and terrain analysis. The conducted tests confirmed the declared accuracy of all tested Czech models (used also in this article). Analysis of terrain measurements of the accuracy of elevation models, carried out by the University of Defence, Brno, and a comparison of the possibilities of using available elevation models with different levels of accuracy were the main prerequisites for a new, as yet unpublished methodology aimed at evaluating the influence of microrelief shapes generated from various elevation models on military mobility. A stereo-vision-based terrain passability estimation method for off-road mobile robots is presented in [5]. The method models surrounding terrain using either sloped planes or a digital elevation model, based on the availability of suitable input data. This combination of two surface-modelling techniques increases the range and information content of the resulting terrain map. As defined in [6], the greatest asset to global elevation models are the TanDEM-X and ALOS projects. The TanDEM-X satellite mission has now mapped the Earth's global topography with a spatial resolution of 0.4 arc-sec (about 12 m). While TanDEM-X is a commercial mission, a down-sampled elevation model (WorldDEM) with a 3 arc-sec resolution (commensurate to SRTM) and global coverage, the ALOS system is a new 3D model of the Earth's surface of up to a 0.15 arc-sec (5 m) resolution. It will be generated from optical stereoscopy carried out aboard the ALOS satellite. The option of comparing various terrain models can be studied from [7]. It assesses uncertainties in a derived slope and aspects from a grid of DEMs. A quantitative methodology was developed for objective and data-independent assessment of errors generated from the algorithms that extract morphologic parameters from grid-based digital elevation model (DEM).