[Gdal-dev] rotations in Get/SetGeoTransform

[Frank Warmerdam]

Stephane Routelous wrote:
> Hi Frank,
> 
> thanks a lot for your answer. I didn't thought about that.
> But I have another question :
> what if I want to convert my image format with the GCPs to a gdal originaly
> supported format( ex : asciigrid ), or reverse ?
> How can I convert those GCPs into/from geotransform ?
> I checked the aaigriddataset.cpp file (as example), and there is no
> reference or conversion from GCPs.

Stephane,

You fundamentally cannot represent the geometry of your data in an ESRI
ascii grid.  The GCPs will be discarded on an export to asciigrid.

You could run your dataset through gdalwarp, and the export the result
to asciigrid.  That is rectify your data into a geometric form that can
be exported to asciigrid.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent