[gdal-dev] Question about .aux.xml sidecar file handling...

[Carl Godkin]

On Wed, Jan 18, 2017 at 2:00 PM, jratike80 <
jukka.rahkonen at maanmittauslaitos.fi> wrote:

> Carl Godkin-2 wrote
> > Hi,
> >
> > I have a geological map in a pair of files called USGS.tif and
> > USGS.tif.aux.xml
> >
>
>
> Hi,
>
> Image is georeferenced with ground control points. I wonder what happens if
> you push it through gdalwarp:
>
> gdalwarp -s_srs epsg:xxxx -t_srs epsg:xxxx USGS.tif USGS_warped.tif
>
> -Jukka Rahkonen-
>
>
>
Hi Jukka,

Good idea, but gdalwarp isn't seeing the GCPs either.

gdalwarp -s_srs epsg:26712 -t_srs epsg:26712 USGS.tif warped.tif
ERROR 1: The transformation is already "north up" or
a transformation between pixel/line and georeferenced
coordinates cannot be computed for USGS.tif.
There is no affine transformation and no GCPs.
Specify transformation option SRC_METHOD=NO_GEOTRANSFORM to bypass this
check.

I don't understand the purpose of the .aux.xml sidecar file.  gdalinfo says
it sees it, but does GDAL not actually read it or use any of the contained
information (GCPs and CRS)?  That's what it seems like.

Thanks,

carl
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