add linear and vertical unit geokeys to .las export?

[andyroo]

To import .las files into ArcMap that are produced with PhotoScan (1.0 preview build 1780) I have to strip and re-add VLR GeoKeys because the PS GeoKeys don't provide linear and vertical units. If I don't do that, I get this error (in CheckLas) and the .las won't import:

WARNING 1: Failed to import spatial reference
           Failed to read LAS linear unit geo-key.

The GeoKeys before and after look like this:

Before:

variable length header record 1 of 2:
  reserved             0
  user ID              'LASF_Projection'
  record ID            34735
  length after header  40
  description          ''
    GeoKeyDirectoryTag version 1.1.0 number of keys 4
      key 1024 tiff_tag_location 0 count 1 value_offset 1 - GTModelTypeGeoKey: ModelTypeProjected
      key 1025 tiff_tag_location 0 count 1 value_offset 1 - GTRasterTypeGeoKey: RasterPixelIsArea
      key 3072 tiff_tag_location 0 count 1 value_offset 26910 - ProjectedCSTypeGeoKey: PCS_NAD83_UTM_zone_10N
      key 3073 tiff_tag_location 34737 count 21 value_offset 0 - PCSCitationGeoKey: NAD83 / UTM zone 10N
variable length header record 2 of 2:
  reserved             0
  user ID              'LASF_Projection'
  record ID            34737
  length after header  21
  description          ''
    GeoAsciiParamsTag (number of characters 21)
      NAD83 / UTM zone 10N|

After:

variable length header record 1 of 1:
  reserved             43707
  user ID              'LASF_Projection'
  record ID            34735
  length after header  40
  description          'by LAStools of Martin Isenburg'
    GeoKeyDirectoryTag version 1.1.0 number of keys 4
      key 1024 tiff_tag_location 0 count 1 value_offset 1 - GTModelTypeGeoKey: ModelTypeProjected
      key 3072 tiff_tag_location 0 count 1 value_offset 32610 - ProjectedCSTypeGeoKey: PCS_WGS84_UTM_zone_10N
      key 3076 tiff_tag_location 0 count 1 value_offset 9001 - ProjLinearUnitsGeoKey: Linear_Meter
      key 4099 tiff_tag_location 0 count 1 value_offset 9001 - VerticalUnitsGeoKey: Linear_Meter

My workaround is to use las2las as follows (for UTM 10):

las2las -i infile.las -remove_extra -remove_all_vlrs -o outfile.las -utm 10N -meter -elevation_meter

[Alexey Pasumansky]

Hello Andy,

Linear and vertical units in LAS export has been added in version 1.1.0 build 1982.