Modify LAS/LAZ files via 3D polylines

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 13

There 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).

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