The Digital Terrain Model (DTM) shows the Earth's surface without vegetation, buildings and other anthropogenic formations. The shape of the terrain is determined both by natural influences (e.g., hills, watercourses) and by human influence (e.g., levees, embankments, trenches). The first version of the DTM was based on aerial photographs from 2010 supplemented by detailed measurements, especially in floodplains and other selected parts of Prague. The terrain model is updated at longer time intervals as required.
In 2023, a new DTM was acquired for which a new lidar data evaluation technology was used with a required density of at least 20 points per m2. The overall accuracy of the terrain model is thus in the order of cm, but it depends on the type of surface for the transmittance or reflectance of the laser beams. The DTM is most commonly used in the form of a 1 m resolution raster or its derivatives such as shaded relief or gradient. From the DTM, contour datasets with one, two or five meter intervals are derived.
For some more detailed analyses or visualizations, it is used in the form of an irregular triangular network (TIN) or it can be defined as a set of measured points on the terrain and mandatory edges (e.g., slope edges and foots, ridge and valley lines).
Sample of Digital Terrain Model
Digital terrain model is provided within opendata both raster with 1m pixel resolution and vector data in GIS or CAD formats.