PDAL on the VDI: Setup and metadata examination
Add PDAL in the module load system
PDAL operates in the NCI module load system. To get started, open a new VDI terminal screen and type:
$ module load PDAL
Investigate the results:
$ module list Currently Loaded Modulefiles: 1) pbs 3) proj/4.8.0 2) gcc/4.7.3 4) pdal/1.3.0-py3.5(1.3.0)
The PBS module is loaded by default on the VDI. What we get alongside PDAL/1.3.0-py3.5 is proj/4.8.0, required for or reprojection tasks in PDAL; and gcc/4.7.3 is loaded as part of the module load process.
Note we have a strong hint here for using PDAL's Python modules later - we need to use Python 3.
Check that PDAL works
A simple operational check is to grab some metadata from a LAS file. We'll use the Geoscience Australia elevation reference dataset, hosted on NCI at /g/data/rr1/Elevation
In particular, we'll use a LiDAR survey flown over Merimbula in 2013:
If you're a GDAL user, PDAL metadata querying will look familiar:
pdal info /g/data/rr1/Elevation/Merimbula0313/z55/2013/Mass_Points/LAS/AHD/LAS/Tiles_2k_2k/Merimbula2013-C3-AHD_7605910_55_0002_0002.las
This will return a long JSON output stream telling you all about the LAS tile you queried, and basic statistics on each of its dimensions.
If you got this far, you have a working PDAL - and you've used it for a metadata query!
...to get some other options and see if you can:
- Return a shorter set of metadata
- In this metadata, find the LAS file format major and minor version (hint - using 'grep' will make your life a lot easier
- Return a polygon showing the geospatial extents of the file you queried.
- try the --metadata flag. Using --summary and --schema tell you other interestings things, but you can't answer the next question with them.
- Look for the 'major version' and 'minor version' fields. Separate them with a full stop to get the version: 1.2
- Try '--boundary'. Is it the same as the 'bounds' field if you use --summary?