Until now LAStools have 2 tools to modify lidar data using shapefiles:
- lasclip clips (or classifies) LiDAR points against polygonal building footprints/swath boundaries.
- lasdistance classifies, flags, or remove points within a specified x/y distance of polygonal segments.
las3dpoly covers the missing z dimension.
This enables the user to modify points along a 3D-corridor within a LiDAR data file.
One possible use for this feature is classifying powerlines.
Below you will find an example of how to classify powerlines:
The sample LAZ file shows an area with some powerlines. However, the lasclassify classification does not classify these lines as powerlines (class 13).
To solve this we supply a shapefile or csv textfile with polyline definitions for said lines.
The shapefile is of shapetype 13 (PolyLineZ, qgis: MultiLineStringZ) or shapetype 15 as a polygon. If a polygon, rather than a polyline is supplied we follow the determining edge lines of the polygon.
las3dpoly.exe -v -i in.laz -o out.laz -poly line.shp -distance 2 -classify 13There are two separate options for running point selection; you can either:
– Specify a radial distance to the 3D polygon
– Specify a vertical and a horizontal distance to the 3D polygon
As a result we can now see the powerlines classified as class 13 (Wire).