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DTMs are widely used especially in civil engineering, geodesy
and surveying, geophysics, and geography. The main applications are:
1. Visualization of the terrain.
2. Reduction (terrain correction) of gravity measurements

(gravimetry, physical geodesy).
3. Terrain analyses in Cartography and Morphology.
4. Rectification of airborne or satellite photos.

5. Extraction of terrain parameters, model water flow or mass
movement.
The problem with DTM data is that it does not contain anything
other than elevation information. While useful for general

visualization purposes, it can be difficult to locate objects precisely on
the terrain model by referencing topographic features (since these can
all seem to look alike).

Some uncertainties and errors can be featured in DTM data:
• The accuracy of a DTM depends on the accuracy of its source
data and on the model resolution.

• Two DTMs produced from the same data will not contain the
same information if their resolution and sampling strategies are
different.

• Analysis and calculations based on existing DTMs may also
introduce error and uncertainty through errors in interpolating points
or fitting surfaces.

Task 3. Answer the questions, using the active vocabulary.

1. What is a digital terrain model?
2. How can DTM be stored in GIS databases?

3. What are the main fields of DTM application?
4. What uncertainties and errors can be featured in DTM data?
5. Can you name some other terrain models?

Task 4. Define whether the following statements are true or
false. Correct the false ones according to the text.

1. Vegetation, buildings and other man-made (artificial) features

are not removed in DTM.
2. Modeling terrain relief via DTM is a powerful tool in GIS
(Geographic Information System) analysis and visualization.
3. The problem with DTM data is that it does not contain any

elevation information.

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