GIS Services: A Closer Look at Digital Terrain Models

Digital terrain Models (DTMs), signifying mathematical representations of the ground’s surface, are necessary for getting the topographic/ relief models of the Earth. Mostly found as rectangular grids, the data files related to DTMs comprise of spatial elevation data backed by the latest GIS technology. These days, experienced terrain modelling teams are equipped to develop detailed and accurate DTMs. Their terrain models can be customized to meet the specific needs of flood plain mapping, contour generation, orthophoto rectification, and so forth. For instance, the digital elevation models (DEMs) developed by GIS companies, are specifically designed to take care of volumetric calculations, 3D modeling and powerline surveys.

Digital tools and techniques are applied for getting the required data for bare Earth (underlying terrain) minus buildings, vegetation, or other features that are either man-made or artificial. Another important area of photogrammetry comprises of Digital Surface Models (DSMs) that comprises of these features along with the more advanced ones. It’s common for laymen and companies looking for terrain models to get confused with regards to DTM, DSM and DEM, the most popular digital terrain models applicable to different industry verticals. Read on to take a closer look at these popular terrain modelling techniques.

Digital Elevation Model(DEM)

  • Ground Control Points (GCPs), Triangulate Irregular Network (TIN), and contours are the inputs of generating DEMs. High-quality digital aerial photography in different resolutions, are also used for the development of DEMs.
  • DEMs are mostly represented as a raster or a grid of squares. When representing elevation, a raster is referred to as a heightmap. Triangular irregular networks (TINs) are vector-based representations of DEMs.
  • DEM data files are useful for referring to a raster or normal grid patterns of spot heights.

Digital Terrain Model (DTM)

  • DTMs can be best described as three – dimensional representations comprising of X, Y, Z coordinates. These digital formats depict elevations, heights, geographical and natural elements (ridge lines, forests, rivers, etc.), and other features.
  • DEMs are incorporating break lines, observations, smart engineering tools, three-dimensional computer graphics, and benchmarked technology tools for developing DTMs. AS DTMs need advanced processing they are more expensive to produce in comparison to DEMs.
  • The input resources of DTMs provide accurate measurements of elevations at differing pixels in line with terrain roughness, interpolation algorithm, sampling density, terrain analysis algorithm, grid resolution, pixel size, vertical resolution, and so forth.
  • The common applications of DEMs relate to the extraction of terrain parameters, development of relief maps and physical models, rectification of satellite imagery/ aerial photography, etc. DTMs are also useful for analyzing terrains related to geomorphology, physical geography, etc.

Digital Surface Model (DSM)

  • DSMs are used for representing the MSL elevations related to the top of manmade features and elements (buildings, vegetations, etc.) along with bare Earth.
  • Filtered DSMs incorporate sophisticated post-processing techniques and equipment that are put to use for the detection of errors. They provide accurate TIN, contours, and scores of other deliverables in client specific formats.

SBL Photogrammetry and Terrain Modelling Services

The GIS teams at SBL work on advanced automatic procedures wherein robust DTM modeling and pyramidal data structures are used for extracting and processing DTM points. They have the expertise to source data in line with different kinds of project specifications. For example, if you require terrain models of very remote areas that have no other source of data captures, then DEMs generated thought DEM extraction via stereo satellite scenes can prove helpful. Get in touch with the GIS services provided by SBL to understand the benefits of DEM, DSM, and DTM data and how they can be leveraged for your organizational needs.

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