[gdal-dev] Can't combine crop_to_cutline & -t_srs ?

[Reaves, Timothy]

Gotcha.  Thanks for both pieces of info.


On Thu, Aug 15, 2013 at 9:33 AM, Even Rouault
<even.rouault at mines-paris.org>wrote:

> Le jeudi 15 août 2013 15:25:47, Reaves, Timothy a écrit :
> > I'm converting some GeoPDF files to TIFF.  I want to crop, and I need to
> > re-project.  I can do one or the other, but, when I combine them, all I
> get
> > is a black output.
> >
> > The base command is:
> > gdalwarp -multi -co "TILED=YES" infile.pdf outfile.tiff --config
> > GDAL_PDF_LAYERS_OFF "Map_Collar","Map_Frame.Projection_and_Grids"
> >
> > Then, I use either:
> > -crop_to_cutline -cutline cutline.csv -overwrite
> > or
> > -t_srs EPSG:3785
> >
> > Either of these works.  Just not both.  Are the two options mutually
> > exclusive?
>
> Thimothy,
>
> According to the gdalwarp manual : "If the OGR layer containing the
> cutline features has no explicit SRS, the cutline features must be in the
> georeferenced units of the destination file.".
>
> CSV have no explicit SRS, so to use -t_srs EPSG:3785, the CSV must be
> itself
> in EPSG:3785
>
> So you could do a preprocessing step :
>
> ogr2ogr -s_srs EPSG:XXXX -t_srs EPSG:3785 cutline_3785.csv cutline.csv
>
> where XXXX is the EPSG code of the GeoPDF
>
> And then use cutline_3785.csv as the value of the -cutline parameter of
> gdalwarp.
>
> >
> > As an aside, when cropping, how do I make the area outside of the image
> > transparent instead of black?
>
> Try adding -dstalpha to your gdalwarp command line.
>
> Even
>
> --
> Geospatial professional services
> http://even.rouault.free.fr/services.html
>
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