LiDAR drones are gaining popularity in the land surveying market. These systems are a particularly good choice for creating surveys over closed tree canopies.
The laser pulses from a lidar unit hit not only the topcover vegetation of an area, but also the underlying ground or structures. By measuring travel time of the laser pulse bare-earth elevations can be classified, allowing users to remove tree canopies or other vegetation, which is impossible with only a photogrammetric drone system.
This article explains how these point clouds and associated classification can be loaded in Virtual Surveyor.
Virtual Surveyor converts the point cloud to a terrain. This is a good approach for digital earth works applications and when you want to create a topographic surface at bare-earth level. Virtual Surveyor is not a point cloud engine, so it is not recommended for mobile mapping and terrestrial scanning.
- Supported point cloud file formats are:
- The point cloud file is converted to a terrain file in the following way:
- The cell size is determined based on the point cloud density.
- The point with the lowest elevation is used for each cell.
- The user can select the available classes (if available) before starting the conversion.
- You set a coordinate system because .las/.laz don’t carry a coordinate system like GeoTIFF files do.
Add a point cloud file
- Create a new (empty) project first.
- Drag & drop the point cloud file or files in the project view.
- If you want to convert the entire point cloud, click Run.
- If you want to select a set of the available classes, click Classes.
- Check the box(es) for the classes you want to include in your terrain.
- Click OK and the window will close.
- Click Run to start the terrain conversion.
- Only the points from the selected classes will be used in the conversion.
- Holes will be interpolated.
- When the conversion ends, Insert the terrain in the view port.
- The hill shade lens is automatically enabled
- LiDAR point clouds don’t have color associated with them and the hill shade lens will result in an enhanced 3D perception of hills, valleys and other reliefs.
- Set the appropriate coordinate system in the menu bar.
- If you don’t know the coordinate system, it is best to set to the coordinate system to Local.
- You can choose between the Metric or Imperial versions.
- Read more on how to set Coordinates Systems here.
Add multiple point cloud files
When you add multiple point cloud files, Virtual Surveyor will test if they overlap or touch. When so, the multiple point cloud files will be merged into one large terrain file.
Hint: If you want to have a terrain file for each point cloud file from a set then drag & drop them one by one in the project view.
Tips & Tricks
- You can use the other terrain lenses to emphasize your terrain. Explore all the terrain lenses here.
- It also works for bathymetry data.
- Virtual Surveyor is not a point cloud engine, and generally is not designed to work with terrestrial and mobile mapping data sources.
- Point clouds from photogrammetry data? You can use them but in this case it is better to use the orthophoto and DSM from the photogrammetry process.
Watch the video