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Terrain Models
Turn millions of laser points into clean, professional terrain surfaces — with a single click. Lidarvisor generates five types of terrain models, each answering a different question about your landscape: how high is the ground? How tall are the trees? How steep is the slope?
No GIS experience needed. This page explains each terrain model type in plain language.
What Is a Terrain Model?
Imagine looking at your survey area from directly above and dividing it into a regular grid of tiny squares (pixels). For each square, you assign a single number — for example, the elevation of the ground in that spot. The result is an image where each pixel stores a measurement value instead of a color. This is called a raster — a grid-based map.
When you view a terrain model in Lidarvisor, the platform turns those numbers into colors so you can see the patterns: low areas in blue, high areas in red, flat areas in one shade, steep areas in another.
All terrain models are delivered as GeoTIFF files — a standard format that preserves the geographic position of each pixel, so you can open them in any GIS or CAD software and they will be correctly placed on the map.
Resolution
When you enable a terrain model in the processing options, you choose a resolution in centimeters. This is the size of each pixel on the ground.
- Small resolution (e.g., 25 cm) → More detail, larger file size. Each pixel covers a 25 cm square.
- Large resolution (e.g., 200 cm) → Less detail, smaller file. Each pixel covers a 2-meter square.
How to choose:
- For detailed engineering work: 25–50 cm
- For general topographic mapping: 50–100 cm
- For large-area overviews: 100–300 cm
Tip: The resolution cannot be finer than the spacing of your LiDAR points. If your points are spaced 50 cm apart on average, a 25 cm resolution will not add real detail — it will just create a larger file.
DTM — Digital Terrain Model
What It Is
The DTM represents the bare ground surface — the shape of the Earth as if all trees, buildings, vehicles, and other objects were removed. It answers the question: "What does the ground look like underneath everything?"
How It Is Created
- Lidarvisor's AI identifies which points are classified as Ground.
- Those ground points are used to create a smooth, continuous surface by filling in the gaps between points (a process called interpolation).
- Any areas where no ground points exist (under dense canopy, for example) are filled in by estimating from the surrounding terrain.
What You Get
- DTM elevation raster — a GeoTIFF where each pixel contains the ground elevation in meters.
- DTM hillshade — a visually enhanced version where simulated sunlight creates shadows, making the terrain shape much easier to see. Think of it like a shaded relief map.
In the Viewer
When you check the DTM in the project tree, you see the hillshade draped over the 3D view. This gives a clear picture of ridges, valleys, slopes, and flat areas.
Common Uses
- Topographic surveying and mapping
- Flood risk modeling (identifying low-lying areas)
- Cut-and-fill volume calculations for construction
- Drainage and water flow analysis
- Contour line generation (done automatically by Lidarvisor)
DSM — Digital Surface Model
What It Is
The DSM represents the top surface — the highest thing at each location. Unlike the DTM, it includes treetops, rooftops, power lines, and any other elevated objects. It answers the question: "What would you see if you looked straight down from above?"
How It Is Created
- All point classes (except noise and power line wires) are used.
- For each pixel, the highest point is used as the elevation value.
What You Get
- DSM elevation raster — a GeoTIFF where each pixel contains the highest surface elevation.
- DSM colorized visualization — a color-coded version using a gradient from blue (low) to red (high).
Common Uses
- Measuring building heights (DSM minus DTM gives building height)
- Line-of-sight and viewshed analysis (what can be seen from a given point?)
- Urban planning and 3D city modeling
- Telecommunications tower placement planning
CHM — Canopy Height Model
What It Is
The CHM shows the height of vegetation above the ground. It is simply the DSM (top surface) minus the DTM (bare ground). Where there is no vegetation, the CHM is zero. Where there is a 20-meter tall tree, the CHM is 20.
How It Is Created
The DTM (bare ground) is subtracted from the DSM (top surface), pixel by pixel. The result is a positive number wherever something stands above the ground.
What You Get
- CHM raster — a GeoTIFF where each pixel contains the vegetation height in meters.
- CHM colorized visualization — a color-coded version: blue/green for low vegetation, yellow for medium, red for tall trees.
In the Viewer
The CHM is particularly useful for quickly spotting the tallest trees, identifying clearings, and understanding the vertical structure of vegetation.
Common Uses
- Forest inventory — measuring tree heights across large areas
- Canopy cover analysis — what percentage of the area is under tree cover?
- Habitat assessment — different wildlife species need different canopy heights
- Fire fuel mapping — tall, dense vegetation represents higher fire risk
- Carbon estimation — taller, larger trees store more carbon
Slope Map
What It Is
The Slope Map shows how steep the terrain is at every location, derived from the DTM. Flat areas have near-zero slope, while cliffs and hillsides have high slope values.
How It Is Created
For each pixel in the DTM, the platform calculates the angle of the terrain surface by comparing its elevation to its neighbors.
What You Get
- Slope raster — a GeoTIFF with slope values.
- Slope colorized visualization — a color-coded map using an international standard classification:
| Color | Category | Slope Angle |
|---|---|---|
| Dark green | Level | 0 – 0.5% |
| Green | Nearly Level | 0.5 – 2% |
| Light green | Very Gently Sloping | 2 – 5% |
| Yellow | Gently Sloping | 5 – 10% |
| Orange | Moderately Sloping | 10 – 15% |
| Light red | Strongly Sloping | 15 – 30% |
| Red | Steeply Sloping | 30 – 45% |
| Dark red | Very Steeply Sloping | > 45% |
Common Uses
- Construction suitability — identifying areas too steep to build on
- Erosion risk — steep slopes are more vulnerable to soil erosion
- Agriculture — determining suitable areas for machinery
- Trail and road planning — routing paths along manageable gradients
- Landslide risk assessment
TIN — Triangulated Irregular Network
What It Is
The TIN is a 3D terrain mesh made of triangles. Instead of a regular grid of pixels (like the DTM), the TIN connects ground points directly into triangles. The result is a faceted, angular surface that follows the terrain closely.
How It Is Different from the DTM
| Feature | DTM | TIN |
|---|---|---|
| Structure | Regular grid of pixels | Irregular mesh of triangles |
| Appearance | Smooth, continuous | Faceted, angular |
| Best for | Analysis, visualization | CAD, engineering |
| File format | GeoTIFF (.tif) | GeoTIFF raster + DXF/SHP/GeoJSON vectors |
What You Get
- TIN raster — a GeoTIFF rendering of the triangulated surface.
- TIN hillshade — a visually enhanced version with simulated lighting.
- TIN vectors (optional) — the actual triangles as polygons, with slope, aspect, and elevation attributes. Available in DXF, Shapefile, and GeoJSON formats.
Common Uses
- Civil engineering design (road, dam, and embankment planning)
- Cut-and-fill volume calculations
- CAD integration — TIN meshes import directly into engineering software
- Stormwater drainage modeling
Choosing the Right Terrain Model
| If You Need... | Use |
|---|---|
| A clean ground surface without vegetation or buildings | DTM |
| The height of the top of everything (trees, buildings) | DSM |
| A map of vegetation height only | CHM |
| A map of terrain steepness | Slope Map |
| A 3D mesh for CAD or engineering | TIN |
You can enable multiple terrain models at the same time during processing. They all share the same credit cost (based on area), so there is no extra charge for generating several types.
Next Step
Now let's look at the vector outputs. Head to Vectorization.