Assessing Uncertainties in Derived Slope and Aspect from a Grid DEM

Qiming Zhou, Xuejun Liu

Research output: Chapter in book/report/conference proceedingChapterpeer-review

8 Citations (Scopus)


Digital elevation data are the most frequently used for computer-based terrain analysis and they form an integral part of today’s GIS data analysis capability. For most GIS-based environmental studies, primary topographic parameters such as slope, aspect, and drainage network are often required for specific environmental models. While derived from digital elevation data, particularly the grid-based Digital Elevation Models (DEM), the parameters often display noticeable uncertainties due to errors (a) in the data, (b) inherent to the data structure, and (c) created by algorithms that derive the parameters from the DEM. Some contradictory results have been reported in evaluating the results of various terrain analysis algorithms, largely because of the variety in the assessment methodologies and the difficulties in separating errors in data from those generated by the algorithms. This chapter reports on an approach to the assessment of the uncertainties in grid-based Digital Terrain Analysis (DTA) algorithms used for deriving slope and aspect. A quantitative methodology has been developed for objective and data-independent assessment of errors generated from the algorithms that extract morphologic parameters from grid DEMs. The generic approach is to use artificial surfaces that can be described by mathematical models; thus the ‘true’ output value can be pre-determined to avoid uncertainty caused by uncontrollable data errors. Tests were carried out on a number of algorithms for slope and aspect computation. The actual output values from these algorithms on the mathematical surfaces were compared with the theoretical ‘true’ values, and the errors were then analysed statistically. The strengths and weaknesses of the selected algorithms are also discussed.

Original languageEnglish
Title of host publicationAdvances in Digital Terrain Analysis
EditorsQiming Zhou, Brian Lees, Guo-an Tang
Place of PublicationBerlin, Heidelberg
Number of pages28
ISBN (Electronic)9783540778004
ISBN (Print)9783642096549, 9783540777991
Publication statusPublished - 21 Feb 2008
EventConference on Terrain Analysis and Digital Terrain Modelling, 2006 - Nanjing, China
Duration: 23 Nov 200625 Nov 2006

Publication series

NameLecture Notes in Geoinformation and Cartography
ISSN (Print)1863-2246
ISSN (Electronic)1863-2351


ConferenceConference on Terrain Analysis and Digital Terrain Modelling, 2006

Scopus Subject Areas

  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Earth-Surface Processes
  • Computers in Earth Sciences

User-Defined Keywords

  • Aspect
  • DEM derivatives
  • Digital terrain analysis
  • Error model
  • Slope
  • Uncertainty


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