Across Cole Hill Towards Filkins Hill
You never could see Filkins Hill so well until this area was freshly cut.
Taken on Sunday March 20, 2011 at Cole Hill State Forest.Why ads? π€ / Privacy Policy π³
You never could see Filkins Hill so well until this area was freshly cut.
Taken on Sunday March 20, 2011 at Cole Hill State Forest.
Find LiDAR Point Clouds on the National Map Downloader: https://apps.nationalmap.gov/downloader/#/
Select Find Elevation Source Data (3DEP) – Lidar, IfSAR
Search for LiDAR Point Cloud (LPC)
Click Export all results as a TXT file and save to a directory.
Then run this Unix command on the text file to download point clouds:
cat data.txt | tr -d '\n' | xargs -d '\r' -I {} wget -c -nc '{}'
Next create a pipeline.txt for pdal with the classification (For DSM, 1 are unclassified points like buildings and treetops, while 2 are ground points, if you want a DEM, you can also make them this way too with Classification of 2:2):
{
"pipeline": [
{
"type": "readers.las"
},
{
"type": "filters.range",
"limits": "Classification[1:1]"
},
{
"gdaldriver":"GTiff",
"resolution": 1.0,
"output_type": "max",
"type":"writers.gdal"
}
]
}
Next convert the point clouds into digital surface model (GeoTIFF), you can use this shell command with xargs to go over each LAS file, using the above pipeline:
ls *.laz | xargs -I {} basename {} .laz | xargs -P3 -I {} pdal pipeline pipeline.txt --readers.las.filename={}.laz --writers.gdal.filename={}.tif
The above command can be somewhat slow depending on how many LAZ point clouds you need to go through and your selected resolution. -P3 sets the number of parallel process (3) which can help speed things up a bit.
Now we have the digital surface models raster that can be used in QGIS for hillshade for 3D.
Build a virtual raster (dsm.vrt) for easy loading into QGIS rather than loading separate files.
gdalbuildvrt dsm.vrt *.tif