Split Ground Points
This command allows you to extract the terrain from a point cloud, by creating a point cloud based on the ground points without vegetation or buildings.
Requirements
Select the point clouds corresponding to the ground and launch the command.
Set the max slope of the terrain to choose the type of terrain that has to be extracted (Flat/Steep). It represents the general slope that can be seen in the terrain.
Choose the direction to extract the terrain.
Set the extraction grid size between points to process the point cloud as a grid. This will give the level of details in the final mesh. A low grid size also means a long computation time.
Choose the extraction strategy according to the type of terrain you want to extract.
Choose what you want as outputs: clouds corresponding to the ground, the noise or with unclassified points.
Notes
Direction: for a typical DTM (Digital Terrain Model), the direction to use would always be the Z axis, as the ground is mainly horizontal. However, another direction can be used if this function is used for example to clean the point cloud of a vertical wall and remove all vegetation points. In more complex projects where a direction cannot be found easily, it is useful to use the option Best Plane, as it will take the normal direction of the best plane of the point cloud.
Extraction strategy: choose the Fast extraction strategy if your data is fairly smooth. The option Check noisy points should be used otherwise. The last option (Local steep slopes) should be used in case of a terrain with locally some steep slopes (ditches for example).