[OSGeo Africa] struggling with gdalwarp

[Tim Sutton]

Hi

> 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!

Regards

Tim

—









Tim Sutton

Co-founder: Kartoza
Project chair: QGIS.org

Visit http://kartoza.com <http://kartoza.com/> to find out about open source:

Desktop GIS programming services
Geospatial web development
GIS Training
Consulting Services

Skype: timlinux
IRC: timlinux on #qgis at freenode.net

Kartoza is a merger between Linfiniti and Afrispatial

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20160901/075e4b95/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: KartozaNewLogoThumbnail.jpg
Type: image/jpeg
Size: 6122 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20160901/075e4b95/attachment-0001.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 455 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.osgeo.org/pipermail/africa/attachments/20160901/075e4b95/attachment-0001.sig>