Basic workflows for importing lidar data to GRASS GIS
If you want to obtain a DEM/DSM in GRASS from .las point cloud use one of the following options:
- binning
- Use r.in.lidar to create raster map using binning. Fast, but leaves holes in the data. Use r.fill.stats to fill the holes (use -k flag).
- Multiple tiles can be then merged by r.patch (since they are raster maps)
- interpolating
- Use v.in.lidar to create vector map with points (you can use -t and -b to not build topology and attribute table and speed up the process)
- Multiple tiles can be merged by v.patch (since they are vector maps).
- This you can interpolate using v.surf.rst.
If the projection of the .las file does not match your GRASS location use one of the following options:
- Use las2las before using r.in.lidar or v.in.lidar. The following
example command is for reprojecting tiles in NAD83/North Carolina in feet (EPSG:2264)
into NAD83/North Carolina in meters (EPSG:3358):
las2las --a_srs=EPSG:2264 --t_srs=EPSG:3358 -i input_spf.las -o output_spm.las - You can create a Location which matches the resolution of the las file and then v.in.lidar to import the points there and finally, go to the desired Location and use v.proj to re-project the data from the other Location.