Digital terrain model (DTM/DEM)
Digital terrain models from GNSS, total station, laser scan and drone data: contours, slopes, earthwork volumes and surface water analysis.
A digital terrain model is a three-dimensional mathematical representation of the ground surface. A DTM (Digital Terrain Model) shows bare earth with buildings, trees and other objects removed, while a DSM (Digital Surface Model) includes all objects; the term DEM usually refers to a height model on a regular grid (raster).
Terrain models are used in the design of roads, railways and pipelines, site grading, earthwork volume calculation, drainage and stormwater modelling, landslide and erosion risk assessment, agriculture and urban planning. Designers cut sections, calculate slopes and quantities directly from the model.
The data source depends on the size of the area and the required accuracy: GNSS RTK (1–2 cm horizontal, 2–3 cm vertical) and total stations for small sites, laser scanning for built-up and complex surfaces, and drone photogrammetry or LiDAR for large areas. The point cloud is classified, ground points are extracted and breaklines such as road edges, crests and channels are added.
The model is built in Civil 3D, Credo or GIS software and delivered in the national grid, WGS-84 or UTM zone 39N and the required height datum.
When you need it
- A road, pipeline or other linear structure is being designed
- Site grading and earthwork volumes must be calculated
- Drainage and stormwater flow need modelling
- Landslide and erosion risk is being assessed
- Terrain data is needed for an urban planning or agricultural project
What's included
- Field survey: GNSS RTK, total station, laser scan or drone
- Point cloud classification and ground extraction
- Adding breaklines
- Building TIN and raster (DEM) models
- Contours and slope maps
- Optional volume and surface water analysis
How we work
- Choosing the area, accuracy and data source
- Control points and field survey
- Processing and classification
- Model building and accuracy check
- Delivery
Deliverables
- Terrain model (TIN: LandXML, DWG; raster: GeoTIFF)
- Contoured topographic plan
- Slope and elevation maps
- Accuracy report
