Re: [gdal-dev] projection in external file

[Frank Warmerdam]

On 11-01-26 08:33 AM, morabit wrote:

Hi All,
  In our project we have to support the loading of tiff images
that will be geo-referenced by means of external companion
files containing the affine geo transformation and projection
information (WKT).
We have tested that GDAL supports external geo-transform
using .tfw files, but we are not able to load WKT info included
in companion .proj or .wkt files.
Does GDAL support this kind of feature?
Perhaps it supports this feature using some other format (aux.xml)?
In case of positive answer, what is the right way to accomplish this?

Bruno,

Yes, it should be possible to embed a coordinate system in an .aux.xml file
and have GDAL utilize it transparently for GeoTIFF files.  I have attached
an example .aux.xml file with a coordinate system and geotransform in it.
Note that the coordinate system is in WKT, but with XML encoding of special
characters like quotes.

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


<PAMDataset>
  <SRS>PROJCS[&quot;NAD27 / UTM zone 11N&quot;,GEOGCS[&quot;NAD27&quot;,DATUM[&quot;North_American_Datum_1927&quot;,SPHEROID[&quot;Clarke 1866&quot;,6378206.4,294.9786982139006,AUTHORITY[&quot;EPSG&quot;,&quot;7008&quot;]],AUTHORITY[&quot;EPSG&quot;,&quot;6267&quot;]],PRIMEM[&quot;Greenwich&quot;,0],UNIT[&quot;degree&quot;,0.0174532925199433],AUTHORITY[&quot;EPSG&quot;,&quot;4267&quot;]],PROJECTION[&quot;Transverse_Mercator&quot;],PARAMETER[&quot;latitude_of_origin&quot;,0],PARAMETER[&quot;central_meridian&quot;,-117],PARAMETER[&quot;scale_factor&quot;,0.9996],PARAMETER[&quot;false_easting&quot;,500000],PARAMETER[&quot;false_northing&quot;,0],UNIT[&quot;metre&quot;,1,AUTHORITY[&quot;EPSG&quot;,&quot;9001&quot;]],AUTHORITY[&quot;EPSG&quot;,&quot;26711&quot;]]</SRS>
  <GeoTransform>  4.4072000000000000e+05,  6.0000000000000000e+01,  0.0000000000000000e+00,  3.7513200000000000e+06,  0.0000000000000000e+00, -6.0000000000000000e+01</GeoTransform>
</PAMDataset>

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