A digital terrain model (DTM or DEM) is a three-dimensional representation of the earth's surface, represented as an array of points with a defined height. The terrain model contains information about the height without considering vegetation, buildings, and other objects. In some countries, digital elevation model is synonymous with digital terrain model. However, in the US and other countries, digital terrain model has a slightly different meaning. A digital terrain model is a set of vector data consisting of regularly spaced points and natural features, such as ridges, inflection lines, etc.
Digital terrain model is a plurality of points with known geodetic coordinates and a rule of height definition of all other points, which are not included into the plurality. Points with known geodetic coordinates are called ground control points (GCP).The rule of height definition is called the rule of interpolation. Methods of DTM generation differ by schemes of GCPs' location and by interpolation algorithms of the intervals between GCPs.
Data on the relief can be collected from geodetic survey or remote sensing, as well as from cartometric works. Thus, there are different ways of setting these data:
Data on the relief can be collected from geodetic survey or remote sensing, as well as from cartometric works. Thus, there are different ways of setting these data:
- with regular location of points on rectangular, triangular and hexagonal grids, which were brought from tacheometric survey or from levelling
- with irregular location of points along structure lines, which were brought from cartometric works
- with isolinear location of points, which was brought e.g. from contour line vectorization
Sources of initial information about the terrain: a variety of data obtained by geodetic works, topographic survey of the area, stereo photogrammetric processing of aerial and satellite images, laser shooting and radar shooting.
The most common methods of digital representation of terrain are as follows:
Organizing the process of creating a digital terrain model or digital elevation model
- Receiving and approving data from the Customer. It is necessary to understand the purpose of creating a digital model of the terrain and elevation model, to know the size and nature of the terrain and the required accuracy of creating products in order to calculate the cost and timing of work, as well as to plan the work.
- Planning and ordering the shooting. Depending on the size of the territory and other information about the object, you can choose and order the type of survey, as well as other source data.
- Processing of materials. The specialized software products available at GEO Innoter allow you to obtain a digital surface model (digital terrain model or digital elevation model) in an automated mode, with the accuracy, form and format required by the Customer
- Transfer of materials to the Customer. We transmit the results of the work to the Customer in the required form and format.
The most common methods of digital representation of terrain are as follows:
- a regular matrix (regular or matrix model) of the earth's surface heights (representation on a regular grid of squares, rectangles, or triangles when its nodes are set to the height values).
- an irregular, so-called TIN-model (TIN − Triangulated Irregular Network), which includes a certain set of points with elevation marks, which are triangulated taking into account the lines of the discontinuity.
- vector lines (horizontal lines or other isolines with equal or unequal pitch); networks (height matrix).
The terrain model in the form of a height matrix can be provided in the following formats:
- GeoTIFF, Arc / Info ASCII Grid (ASC), Band interlieved (BIL), XYZ, or as tiles in Sputnik KMZ format
- DEM as a TIN model can be provided in the following formats: Wavefront OBJ, 3DS, VRML, COLLADA, Stanford PLY, STL models, Autodesk FBX, Autodesk DXF, Google Earth KMZ, U3D Universal 3D, Adobe PDF.
- Horizontal lines (isohypses) are provided in the following formats: Autodesk DXF, Shapefile SHP, Google KML.an irregular grid.
Using a digital terrain model:
- For mapping purposes to build a digital surface model; • Forecasting of landscape processes (where water will accumulate, in which place it is better to plant plants, etc.
- Territorial planning
- Design of buildings and structures.
- Construction of highways, highways, and interchanges.
- Environmental problems (including modeling of environmental situations).
- Building a digital model of the bottom relief of reservoirs.
- Study and quantitative assessment of the current state of the natural environment.
- Household use of digital modeling in GIS – electronic maps, navigators.
ADVANTAGES OF " GEO INNOTER»:
- Extensive experience in creating digital terrain models;
- The highest qualification for working with remote sensing materials)
- Modern software for stereo photogrammetric processing of remote sensing materials
- GEO INNOTER LLC is accredited by the Ministry of Justice of the Russian Federation in the direction of conducting expertise on remote sensing materials
- Cooperation agreements with all the world's leading remote sensing operators.
To calculate the cost of creating DEMs, DTMs, orthophotoplanes and other products for the territory you need, send the technical specification to the email address: innoter@innoter.com. For more information, please call: +7 495 245-0424.