From Survey to Terrain Model

A terrain model can be created based on two types of survey data:

• Field data with X, Y, Z coordinates via GPS or total station
• 3D scan data Point Cloud via laser/drone

Field data with X, Y, Z coordinates

When surveying the terrain, it is important to consider that the data will be used to calculate a DTM (Digital Terrain Model).

• Points: Ensure there are enough elevation points. It is pointless to calculate a DTM if there are insufficient points that can be considered in the calculation. It is recommended to measure enough elevation points based on the project’s needs.

• Lines: Breaklines. Measuring significant breaklines is advisable. These are lines that represent a break between two different slopes, such as ditches, the bottom, and top of embankments, etc. It's not necessary to measure many points if the breaklines are well-defined in the terrain. Breaklines can include lines, arcs, circles, and curves (e.g., the edge of a pond).

• Layers: Although not mandatory, using layers can be a helpful tool. You can categorize your survey data by using codes or comments and group them into layers. Working with layers allows you to hide objects that aren’t needed for the terrain model calculation, leaving only those that should be considered. This simplifies the selection of objects for the calculation. As an example this will enable you to set layers with buildings or vegetation to invisible for the DTM calculation.

1. Select points. Optionally, also select breaklines and a polygon that defines the area of your DTM.

2. Go to DTM > New Terrain Model.

Name: Enter a name for the terrain model you are about to create. Pythagoras can calculate up to 256 different DTMs in one drawing, so clear naming is essential.

• Ensure your selection includes points. Use the elevations of the points or a numeric field from a table.
• Your selection contains lines. Use these as breaklines: yes/no.
• Your selection contains a polygon. Use this as a boundary polygon: yes/no.

Click 'OK'.

3. Warning: If your selection contains a polygon.

See Result

Point Cloud

After importing a Point Cloud. 

1. Go to DTM > New Terrain Model.

Name: Enter a name for the DTM you are about to create. Pythagoras can calculate up to 256 different DTMs in one drawing, so clear naming is essential.

• For Use point cloud, choose the point cloud you want to create a DTM from.
• Reduce density: Choose this option to reduce the number of points in the DTM. If there is a higher point density in an area, the highest points will be skipped and won’t be used for the DTM calculation. In areas where the density is lower than the specified threshold, all points are kept for the calculation.

Click 'OK'.

Result

As a result, a terrain model will appear, displaying triangulations in green.

You can find the DTM in the overview via Active Settings, where you can further refine or adjust it.