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Digital Elevation Models / Digital Terrain Modelling(DEM/DTM)

The earths surface is a continuous phenomena. There are various ways of representing such surfaces in digital form using a finite amount of storage.

DTM
A digital terrain model (DTM) can be described as a three - dimensional representation of a terrain surface consisting of X, Y, Z coordinates stored in digital form. It includes not only heights and elevations but other geographical elements and natural features such as rivers, ridge lines, etc. With the increasing use of computers in engineering and the development of fast three-dimensional computer graphics the DTM is becoming a powerful tool for a great number of applications in the earth and the engineering sciences.
DEM
A DEM is a quantitative model of a topographic surface in digital form. The term digital elevation model or DEM is frequently used to refer to any digital representation of a topographic surface, however, most often it is used to refer specifically to a raster or regular grid of spot heights.
Methodology and Quality

Height information from the terrain surface in regular grid form gives a digital terrain model. The quality of a DTM is directly dependent on the grid interval and the data source from which it is generated. Depending on the required application information about breaklines and embankments will be incorporated. The DTM is visualised through, for example, 3D-wire mesh models with coloured height columns. Contour lines, cross sections, slope models or volume calculation can also be derived from a DTM.

A sufficient amount of height information is necessary in order to calculate a DTM. Such information is gathered from the photogrammetric restitution of spot heights and breaklines in aerial photos (vector data) or from laser scanner mapping. The program doesn’t only generate the DTM, but also provides a variety of processes for analysis and visualisation.

Using the software a dense point cloud of heights is first generated. This is done simultaneously in multi images through automated elevation collection (correlation). Then using a powerful editing tool the operator checks the results and efficiently correct them. Elevation points on man-made structures or vegetation can be eliminated and gaps filled. As a final step the DTM is generated.

The generated DTM plays a major role in the production of geo-referenced aerial photos i.e. digital orthophotos.

DTM/DEM Generation @ Stesalit
Stesalit maintains a team of experienced professionals who have delivered the best results in DTM/DEM generation using conventional and LIDAR data. Speed and consistency remains intrinsic to our processing methodology as we produce digital terrain models (DTMs) and digital elevation models (DEMs) for specialized applications such as
  • Resource Management
  • Land-use modelling (e.g., slope stability, forest fires, agricultural production)
  • Pollution monitoring and environmental management
  • Earth Sciences
  • Hydrological modelling
  • Earth surface process modelling
  • Civil and Military Engineering
  • Line-of-sight assessment
  • Aspect analysis
  • Accessibility studies
  • Battle planning
  • Surveying and Photogrammetry
  • Data storage and visualization
  • Production of orthophotography
Copyright©2008 Stesalit. All rights reserved