LAS header coord sys GeoKeys incorrectly read by ArcGIS?

[BradyCallahan]

We just ran into an issue trying to get ArcGIS LAS Datasets and Mosaic Datasets to correctly interpret the coordinate reference system in a LAS 1.2 file header. The LAS 1.2 spec uses the GeoTIFF GeoKey tags as opposed to the newer 1.4 spec which uses the WKT. Does anyone know which GeoTIFF GeoKeys translate to form the Geographic Coordinate System (GCS) portion of an ESRI defined coordinate system?

We tried to define a GCS_North_American_1983 using:

key 2050 - GeogGeodeticDatumGeoKey: Datum_North_American_Datum_1983 

key 2056 - GeogEllipsoidGeoKey: Ellipse_GRS_1980

but for ArcGIS this resulted in:

Datum: D_North_American_1983

Spheroid: GRS_1980

Semimajor Axis: 6378137.0

Semiminor Axis: 6378137.0

Inverse Flattening: 0

I'm wondering if perhaps instead we should be using:

key 2048 - GeographicTypeGeoKey: GCS_NAD83

key 2056 - GeogEllipsoidGeoKey: Ellipse_GRS_1980

Does anyone know this spec and how to have it correctly interpreted?

[IanMurray]

Melita Kennedy​, something you could help with?

[BradyCallahan]

I checked in with Melita and Clayton Crawford yesterday about this and neither one knew the answer.

[JohnBrodnicki]

I do not understand how ArcGIS interprets the coordinate reference system in the header files but we did run into a similar issue. The coordinate reference system for a number of files was not being read properly in Arc. The header files looked correct but there were some minor differences between the problem files and those being read correctly. We ended up using las2las (project) in lastools to get the file's coordinate system read properly by ArcMap. The original coordinate reference system was left blank and the correct reference system was entered in the output coordinate system. The re-projected files were read correctly by ArcMap.