Support for geotiffs with ModelTransformation but without ModelPixelScale

[beihl]

GEOTiffs without ModelPixelScale but WITH ModelTransformation are possible ::
http://geotiff.maptools.org/spec/geotiff2.6.html#2.6

Currently getResolution() fails for these images.

[beihl]

Here is how GDAL's geotiff driver handles this :

If GeoPixelScale exists:
https://github.com/OSGeo/gdal/blob/trunk/gdal/frmts/gtiff/geotiff.cpp#L14372
ELSE if ModelTransformation exists :
https://github.com/OSGeo/gdal/blob/trunk/gdal/frmts/gtiff/geotiff.cpp#L14457

[constantinius]

Thanks, good catch. Do you happen to have a test file with that condition you are willing to share so that I can make an automated test for this?

[beihl]

Sure.
no_pixelscale_or_tiepoints.tiff

[constantinius]

Okay, this is done with 5ab27ad, 1c6b5ad and tests with fc05fee

Could you test this yourself?
Btw: I referenced your image in the test setup script, would it be possible to leave it there?