[Liblas-devel] ECEF?

[Frank Warmerdam]

Ben, and others,

I have completed preliminary changes in liblas and GDAL for Geocentric
support.  To use it you will need GDAL "trunk" and liblas "trunk".  With
these updates it is possible to write geocentric geotiff tags as well as
"WKT".  A sample file in geocentric coordinates is available at:

   http://home.gdal.org/tmp/geocentric.las

This is the file srs_utm17.las from the source tree transformed with:

   las2las -i srs_utm17.las --t_srs EPSG:4328 -o geocentric.las

A portion of the lasinfo report on this files looks like:

   Min X Y Z:                   568010.21 -4929965.66 3993511.40
   Max X Y Z:                   568014.31 -4929963.72 3993512.92
   Spatial Reference:
GEOCCS["WGS 84 (geocentric)",
     DATUM["WGS_1984",
         SPHEROID["WGS 84",6378137,298.257223563,
             AUTHORITY["EPSG","7030"]],
         AUTHORITY["EPSG","6326"]],
     PRIMEM["Greenwich",0],
     UNIT["unknown",1]]

Geotiff_Information:
    Version: 1
    Key_Revision: 1.0
    Tagged_Information:
       End_Of_Tags.
    Keyed_Information:
       GTModelTypeGeoKey (Short,1): ModelTypeGeocentric
       GTRasterTypeGeoKey (Short,1): RasterPixelIsArea
       GTCitationGeoKey (Ascii,20): "WGS 84 (geocentric)"
       GeographicTypeGeoKey (Short,1): GCS_WGS_84
       GeogLinearUnitsGeoKey (Short,1): Linear_Meter
       GeogAngularUnitsGeoKey (Short,1): Angular_Degree
       GeogSemiMajorAxisGeoKey (Double,1): 6378137
       GeogInvFlatteningGeoKey (Double,1): 298.257223563
       End_Of_Keys.
    End_Of_Geotiff.

If there is anyone else who has produced LAS files in geocentric (ECEF)
coordinates with appropriate coordinate system information I would be
interested in examining the files.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent