[pdal] "Unknown" values in WKT string

[Alexandre Poirot]

Hello all,

I am trying to understand a behaviour of PDAL 2.1.0 regarding LAS file reading.

I have a LAS 1.4 file which have the following content as its WKT string:

----------
COMPD_CS["NAD83(2011) / Alabama West + Ellipsoid
(Meters)",PROJCS["NAD83(2011) / Alabama
West",GEOGCS["NAD83(2011)",DATUM["NAD83_National_Spatial_Reference_System_2011",SPHEROID["GRS
1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","1116"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","6318"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",30],PARAMETER["central_meridian",-87.5],PARAMETER["scale_factor",0.999933333],PARAMETER["false_easting",600000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],AUTHORITY["EPSG","6356"]],VERT_CS["Ellipsoid
(Meters)",VERT_DATUM["Ellipsoid",2002],UNIT["metre",1.0,AUTHORITY["EPSG","9001"]],AXIS["Up",UP]]]
-----------

I got this file from a colleague.

When I run the command (configuration: Archlinux with Linux 5.8 kernel):

----------
pdal info --metadata <myfile>
----------

I obtain the following result for the spatial reference:

----------
"spatialreference": "COMPD_CS[\"unknown\",PROJCS[\"NAD83(2011) /
Alabama West\",GEOGCS[\"NAD83(2011)\",DATUM[\"NAD83_National_Spatial_Reference_System_2011\",SPHEROID[\"GRS
1980\",6378137,298.257222101,AUTHORITY[\"EPSG\",\"7019\"]],AUTHORITY[\"EPSG\",\"1116\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AUTHORITY[\"EPSG\",\"6318\"]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"latitude_of_origin\",30],PARAMETER[\"central_meridian\",-87.5],PARAMETER[\"scale_factor\",0.999933333],PARAMETER[\"false_easting\",600000],PARAMETER[\"false_northing\",0],UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],AXIS[\"Easting\",EAST],AXIS[\"Northing\",NORTH],AUTHORITY[\"EPSG\",\"6356\"]],VERT_CS[\"unknown\",VERT_DATUM[\"unknown\",2005],UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],AXIS[\"Up\",UP]]]"
----------

I don't understand why and where the COMPD_CS, VERT_CS and VERT_DATUM
are filled with "unknown" while it is defined in the LAS file.
There is also some messages displayed in the console (6 to be thorough):
"proj_uom_get_info_from_database: unit of measure not found"

So my first question is do you know why this behavior is happening?
A second question is can I trust the point positions that PDAL read
from the LAS file with the "unknown" being present in the srs?

Could "Ellipsoid" be a user defined coordinate system that my proj
installation doesn't know?

Should I open an issue on the Github repository?

By the way, congratulations for the great work you've achieved so far
on this library!

Best regards,
Alexandre Poirot | Software Engineer
Route de Renens 24 | 1008 Prilly, Switzerland
alexandre.poirot at pix4d.com
https://www.pix4d.com/