Update Geocoding

There are two tools in GeoCue that can be used to update the coordinate reference system information found in the header of an LAS file. Both of these tools are normally found in the Utilities tab of standard LAS Working segment checklists or may be added to your custom checklist using Environment Builder.

Update Geocoding

The step can be found on the Utilities tab of the LAS Working Segment checklist, or you can add it to the appropriate portion of your custom checklist using Environment Builder.  The tool can be run against multiple LAS Working Segments at once as in standard GeoCue multi-entity processing and can also be dispatched, or distributed for processing using GeoCue’s command dispatch system .

The Update Geocoding step updates the LAS file geotags (GeoTIFF or WKT depending upon the version) will be updated to match the GeoCue layer coordinate system.  This simply updates the tags, it doesn’t implement any reprojection of the point data. When GeoCue writes a LAS v1.4 file it will correct and properly format the georeference information as Open Geospatial Consortium (OGC) well known text (WKT) in the headers as per the new specification. Please note you may have to make some modifications to create WKT adherent to USGS desires.

Update LAS File

The step can be found on the Utilities tab of the LAS Working Segment checklist, or you can add it to the appropriate portion of your custom checklist using Environment Builder.  The tool can be run against multiple LAS Working Segments at once as in standard GeoCue multi-entity processing and can also be dispatched, or distributed for processing using GeoCue’s command dispatch system .

To update a LAS file, specify the version you want to convert to in the first section.  Typically this will be V1.4.  Also specify if you want to update the PDRF version to include the additional core bytes (PDRF 6, 7 or 8). If you select this option, GeoCue will automatically determine if your data is PDRF 6, 7, or 8 based on the data file itself, you do not need to specify.  Note you can generate V1.4 files preserving PDRF versions of 0-5, LAS V1.4 does not require PDRF 6 or higher.  However, most V1.4 deliverables, such as to USGS, will likely be in LAS V1.4 PDRF 6-8.

The second section of the dialog specifies how to handle the classification byte when up-converting to LAS V1.4.  This byte can either follow the official LAS standard classification byte definition consisting of four flags (e.g. withheld) and 32 standard classes, or commonly (but not the official LAS standard in V1.1 – 1.3) 256 classes with no flags (the full byte).  In LAS V1.4 this single byte gets expanded into two bytes.  If you have flags set in your data, and you want to preserve these during conversion, you will specify the first option.  If you are not using flags, and have an extended class table (> 32 classes), and want to preserve the classifications during the conversion you will specify the second option.  GeoCue will then handle the upper bits of the classification byte appropriately as flags or classes during the conversion.

You can also chose to update the header information for file creation date and system identifier.

Finally, if you chose to update the geocoding, the LAS file geotags will be updated to match the GeoCue layer coordinate system.  This simply updates the tags, it doesn’t implement any reprojection of the point data. When GeoCue writes a LAS v1.4 file it will correct and properly format the georeference information as Open Geospatial Consortium (OGC) well known text (WKT) in the headers as per the new specification. Please note you may have to make some modifications to create WKT adherent to USGS desires.

 

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