Le mardi 01 juillet 2014 15:50:18, Jesse McGraw a écrit : > On Mon, Jun 30, 2014 at 3:07 PM, Even Rouault > <[email protected]> > > wrote: > > That might the problem. If you create the GCPs on the PDF and not on the > > PNG, > > and that the PDF has rotation, pdftoppm I think will apply the rotation, > > hence > > the axis swapping. > > Remember, I'm using the PNG I've created for all gdal operations, gdal > never interacts with the source PDF > > I'm probably fundamentally misunderstanding some aspect of the command > lines I'm using in gdal*. My end goal is to get the necessary affine > transformation information to display the PNG I create in step 3a properly > in a separate Android moving-map application (eg. your current position > displayed on the diagram as you move around the airport)
Jesse, hum ok, with the images I think I now understand the situation (I've only looked at the landscape diagram) and what you want. You probably don't want to use gdalwarp, which by default will result in a north-up image. You likely want to compute the geotransform affine matrix for your GCPs and set it, since indeed your GCPs define a 1st-order transformation. The GDAL C API has GDALGCPsToGeoTransform() which does exactly this. I see it is also available in the Python API : gdal.GCPsToGeoTransform(). See http://svn.osgeo.org/gdal/trunk/autotest/gcore/gcps2geotransform.py for how to use it. You could then just do a CreateCopy() of the PNG to a VRT, and set the returned geotransform by the previous step with SetGeoTransform(). Even -- Geospatial professional services http://even.rouault.free.fr/services.html _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
