DOI: 10.5593/sgem2012/s11.v3010


Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 3, 417 - 424 pp


Digital elevation models (DEM) are models that approximate a topographical surface.
These models will contain both random and systematic errors that create uncertainty, or
unreliability, in elevation measurements. Uncertainty can be defined as a lack of
knowledge about the reliability of a measurement, whereas error is the departure of a
measurement from its true value. This error is hardly quantifiable very often and is
defined as the difference between reality and a representation of reality. In the other
hand, quantifying data uncertainty is an important part of spatial analysis, and
researchers are still developing methods to assess, describe and reduce random and
systematic DEM uncertainty.
The common methods used for the assessment of the accuracy of digital elevation
models - DEMs (like root mean square error or mean absolute error) are only global
non-spatial measures. Their unquestionable advantages are their easy calculation and
interpretation. However, as to environmental applications, the knowledge of spatial
error variability is very important. Many authors claim that the extent of errors in a
DEM depends on a character of a terrain and is spatially variable.
The attempts to express the magnitude of error in a space led to the emergence of
different methods for spatial visualization of DEM accuracy. Visualizations bring quick
and easy method how to be informed about precision of the model and how to
understand the nature of the data. The uncertainty has to be also incorporate for deeper
understanding of the model in the light of the previous statement. Several visualization
techniques for portrayal uncertainty in DEM have been developed, but there is a gap
between transferring knowledge between researchers and final users due to lack of
knowledge about the effectiveness of these visualizations. An approach incorporating
effectiveness of uncertainty visualization on the decision making processes is still
missing. The paper deals with the problem of choosing suitable method of uncertainty
visualizations based on perception and cognition studies as a tool for the quality
assessment of the digital elevation models.

Keywords: uncertainty, error, spatial visualization, DEM, quality assessment

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