What is a Digital Terrain Model (DTM)?

A Digital Terrain Model strips away trees, buildings, and everything above ground to reveal the bare earth beneath. Think of it as an X-ray of the landscape — showing only the natural topography without any man-made structures or vegetation obscuring the view. For engineers, surveyors, and environmental scientists, the DTM is often the most critical deliverable from a LiDAR survey.

How DTMs Are Created

Creating a DTM starts with a classified point cloud. Ground classification algorithms analyze millions of LiDAR returns, separating points that hit the actual earth from those that bounced off vegetation, buildings, or other objects. This isn't a simple height threshold — sophisticated algorithms consider local slope, point density, and neighborhood relationships to make accurate decisions even in challenging terrain.

Once ground points are isolated, they're interpolated into a continuous raster surface. The resolution you choose (typically 0.5m to 2m) balances detail against file size and processing time. Areas with sparse ground returns — like dense forests — require careful gap-filling to avoid artifacts.

Why DTMs Matter

The applications are vast. Hydrologists use DTMs to model water flow and predict flood extents — water doesn't care about trees, only the ground beneath them. Civil engineers calculate cut-and-fill volumes for construction projects, where accuracy directly impacts budgets. Archaeologists have discovered ancient roads, fortifications, and settlements hidden under centuries of forest growth, visible only when vegetation is digitally stripped away.

The difference between a DTM and its counterpart, the DSM (Digital Surface Model), reveals object heights. Subtract one from the other, and you instantly know how tall every building and tree stands.

DTMs with LidarVisor

LidarVisor's AI automatically classifies ground points and generates production-ready DTMs. Export as GeoTIFF, hillshade visualization, or contour lines — no desktop GIS required.