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Author Topic: Possible bug with LAS export in VLRs/GeoKeys.  (Read 3462 times)

andyroo

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Possible bug with LAS export in VLRs/GeoKeys.
« on: July 03, 2013, 11:44:46 PM »
I had a problem importing .las files from PS 0.9.1 to ArcGIS 10.1 until I stripped out VLRs and manually added projection information back in with las2las (part of LAStools).

Using lasinfo, I was able to identify some suspicious VLRS for my projection (esp. key 3). I am not sure what the "forgiveness" of interpreting GeoKeys is supposed to be, and not very familiar with .las specification, so I don't know whose "fault" it is, but I did have to change things before a .las exported from PhotoScan could be used in ArcGIS:

Here's lasinfo report on the VLRs before I ran las2las:

    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 2285 - ProjectedCSTypeGeoKey: look-up for 2285 not implemented
      key 3073 tiff_tag_location 34737 count 32 value_offset 0 - PCSCitationGeoKey: NAD83 / Washington North (ftUS)


and my command line was:

las2las -i GLI_Sparse.las -remove_extra -remove_all_vlrs -o GLI_Sparse_reproc.las -sp83 WA_N -feet -elevation_feet

and the resulting (working) keys were:

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 32148 - ProjectedCSTypeGeoKey: PCS_NAD83_Washington_North
      key 3076 tiff_tag_location 0 count 1 value_offset 9002 - ProjLinearUnitsGeoKey: Linear_Foot
      key 4099 tiff_tag_location 0 count 1 value_offset 9002 - VerticalUnitsGeoKey: Linear_Foot


I thought this might be worth posting in case the "look-up for 2285 not implemented" text was a bug...

Andy