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Suitable digital elevation model

Tomaž Podobnikar
Tomaž Podobnikar
Research Fellow
Institute of Anthropological and Spatial Studies
Scientific Research Centre of the Slovenian Academy of Sciences and Arts
Novi trg 2
SI-1000 Ljubljana
Tel: +386 1 470 64 93
Fax: +386 1 425 77 95

Digital elevation model (DEM) is one of the most important datasets for the greater part of spatial-based studies and research. A high quality DEM could be generally used as all-purpose dataset, but unfortunately its production could be very expensive. If we know a nature of application that applies DEM and if our demands for the final result are clear, then we can adjust the DEM selection or we can simplify its production.

Generation or selection of a digital elevation model (DEM) suitable for different spatial analyses or visualisation purposes is being discussed here. At the first we should stress that DEM is only a model, that is approximation of the nature and its nominal ground. The models, in our case DEMs, might be different concerning their purpose of use, quality of data sources or interpolation algorithms, experiences of operator, etc. Our starting point is that the DEM should be carefully produced or chosen regarding purpose of our applications.

In general, more course analyses require lower accuracy DEM than detailed ones. We suppose that DEM for producing contour lines (in any scale) or to emphasize the main characteristics of the geomorphology, should be more course and smoother than the DEM for calculating slopes or aspects. Modelling of hydrographical networks requires geomorphologically correct DEM. To get overview of the geomorphology or visualisation of the whole Alps, the DEM could be carefully generalised from more detail data or appropriate modelled. For the analyses of natural landscape or ancient environment, the recent anthropogenic changes (stone quarries, dykes) should be eliminated. For the palaeo-landscape analyses, geological changes should be considered…

Anyway, we assume that the final user should be aware of the characteristics, cost and usability for particular application before to decide between using of the existing DEM or employing its own DEM production. Here exists also a third option, adopting existing DEM to own needs. For the correct decision is important also considering many other elements of the required DEM, like quality parameters including positional and temporal accuracy, completeness, lineage, etc.

If we are decided to produce our own DEM or to adopt existing DEM, then it is important to select suitable software for interpolation and to take into account quality of the data sources for DEM modelling. In the next chapters we will demonstrate simple tests of the different algorithms using the same basic data sources. Further on we will enhance the DEM production with fusion data sources of different quality and type. These procedures are educational for understanding the management of data sources and DEMs themselves to get the final suitable DEM for required needs.

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