This may also relate to a recent question on "Unknown" values in WKT strings. I'm trying to create EPT files where my horizontal coordinates are in NAD83 UTM and my vertical are ellipsoid heights. There isn't a lot of information that I could find about how to set up the reference system for something like that. The recommendations in the OGC GeoTIFF documentation suggest you could do something like putting the projected 2D CRS in the horizontal and the code/description for the geographic 3D reference system in the vertical. There is no EPSG code for NAD83 ellipsoid heights except as part of a 3D reference system.
Do you have any idea how I can specify those coordinates such that entwine or pdal will understand it? They currently do not recognize the 3D CRS code (e.g. 6319 for NAD83(2011) ellipsoid) as a legitimate vertical choice. Is there a WKT for this that just isn't well known to me? I think it isn't only NAD83 that has this issue. I have checked in with EPSG on this before. The response didn't get me very far, but I'll put it here in case it helps someone else.
While it seems like the EPSG answer says my reference system isn't valid, I'm not convinced. Lidar collections are going to start in the 3D coordinate system (lat, lon, ellipsoid heights). If they then have a geoid applied to get to orthometric prior to projecting, that seems to be considered valid (e.g. NAD83 UTM + NAVD88), but if you don't apply the geoid, it's invalid. That makes no sense.
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I reached out to Even and he asked the GeoTIFF group. The discussion on the topic you might participate in is at https://github.com/opengeospatial/geotiff/issues/82
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