Creating a Digital Terrain Model (DTM) Using 3Dsurvey’s Point Cloud Classification Wizard.
Starting with a Calculated Point Cloud
Begin with a point cloud (Level 1) that contains obstructions like buildings, cars, and vegetation. These must be removed to isolate terrain points, which can be done manually or using the classification wizard.
In the Point Cloud tab, select the Classification function. The wizard will open with default parameters. Check the Smoothing Factor box and click Next.
Selecting Terrain Patches and Deleting Non-Terrain Points
Choose terrain patches across the point cloud for the software to detect the terrain automatically. Ensure selection covers the entire point cloud, then click Next.
Review the automatic detection results. If needed, add or modify terrain areas. Once satisfied, click Finish to complete the classification process.
The classified terrain points will appear in red, with non-terrain points in other colors. Make final adjustments and click Delete Other to remove non-terrain points.
Calculating the Digital Terrain Model
With a clean set of terrain points, navigate to the DSM tab, select Calculate New, and click Calculate. This generates your Digital Terrain Model (DTM).