[pdal] proper syntax for applying a geoid in newer PDAL versions

[Matt Beckley]

Hello,

In older versions of PDAL I used to be able to run a pipeline like:

*{"pipeline": [{"type" : "readers.las",*
*                  "filename": "input_Ellipsoidal.laz"},*
*                 {"type":"filters.reprojection",*
*                  "in_srs":"EPSG:32611",*
*                  "out_srs":"+init=EPSG:32611
+geoidgrids=g2003conus.gtx"},*
*                 {"type" : "writers.las",*
*                  "filename": "output_withGeoid.laz",*
*                  "compression": "laszip",*
*                  "a_srs": "EPSG:32611+5703"*
*                 }]}*


This would run fine, and the output would have the geoid properly applied.

However, newer versions of PDAL (e.g. 2.5.3) uses newer version of PROJ,
which no longer likes its string in the form, "+init=epsg:XXXX".  It will
give the warning:
"Warning 1: +init=epsg:XXXX syntax is deprecated. It might return a CRS
with a non-EPSG compliant axis order."  When running the above pipeline in
newer versions of PDAL, I get the above warning, and the output grid does
not have the geoid applied.

I tried adjusting the PROJ string to remove this convention:

*{"pipeline": [{"type" : "readers.las",*
*                  "filename": "input_Ellipsoidal.laz"},*
*                 {"type":"filters.reprojection",*
*                  "in_srs":"EPSG:32611",*
*                  "out_srs":"*+proj=utm +zone=11 +type=crs
* +geoidgrids=g2003conus.gtx"},*
*                 {"type" : "writers.las",*
*                  "filename": "output_withGeoid.laz",*
*                  "compression": "laszip",*
*                  "a_srs": "EPSG:32611+5703"*
*                 }]}*

This runs without warning or errors, but again, the output grid does
not have the geoid applied.  Most of the documentation on this type of
operation I've seen still refers to the older PROJ syntax of,
"+init=epsg:XXXX".

Is there a way to apply a geoid with the new PROJ syntax, and hopefully I
am just missing something with the proper syntax to do this operation on
the newer versions of PDAL?

Thanks!
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