[OSGeo Africa] struggling with gdalwarp

Tim Sutton tim at kartoza.com
Thu Sep 1 11:38:32 PDT 2016


> On 01 Sep 2016, at 3:55 PM, Zoltan Szecsei <zoltans at geograph.co.za> wrote:
> Hi Guys,
> I've been struggling to get some 3200 orthos mosaicked and tiled.
> They are very old and have really bad projection definitions, pixel sizes and metadata funnies.
> I'm down to the last 261, and have hit a brick wall, likely due to my not that great "projection definitions" knowledge.
> I get the following error from gdalwarp:
> ERROR 6: Unable to load PROJ.4 library (libproj.so), creation of
> OGRCoordinateTransformation failed.
> I have tried various different gdalwarp parameters - even leaving gdalwarp to sense in input projection and me only specifying the output projection.
> If I leave out both s_srs and t_srs then gdalwarp does work but obliviously does not reproject to Lo19.
> I have even tried feeding the output of this redundant gdalwarp into a gdalwarp with t_srs, but no success.
> Specifying only t_srs (as above) on many other orthos on Lo17 & Lo21 does work so it is likely that the way this projection is embedded in this ortho is the problem.
> I have tried stripping it out with gdal_edit.py but haven't gotten that right yet.
> Anyone with pointers or ideas on this?

Have you tried using the corner coordinates and centre to georeference the image. I assume the corner & centre coordinates reported are correct and in LoXX ? There is an example of how to do this in the first reply of this stack exchange post:

http://gis.stackexchange.com/questions/38987/how-can-i-add-all-the-4-corners-as-gcp-in-an-image-that-i-want-to-reproject <http://gis.stackexchange.com/questions/38987/how-can-i-add-all-the-4-corners-as-gcp-in-an-image-that-i-want-to-reproject>

Hope that helps!




Tim Sutton

Co-founder: Kartoza
Project chair: QGIS.org

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