[MapProxy] Distortions in EPSG 4236 -> 900913 reprojection

[Oliver Tonnhofer]

Hi Andreas,

On 26.11.2010, at 21:36, Andreas Trawoeger wrote:
> When I try to use mapproxy for reprojecting from EPSG 4236 to 900913
> the far right side of my maps gets distorted.
> With a world map and zoom level 0 the distorted area from about 140 to
> 180 degree longitude and the problem persists on every zoom level
> focusing near 180 degree longitude.
> 
> Thats probably a bug in my libproj installation (I'm using Ubuntu
> 10.10), but when I'm try to to the same in GDAL everything works fine.

I can reproduce the error. libproj wraps around at the date line and transforms a point at 180.001 to -179.999 (in 900913). That messes up the pixel coordinates for the image transformation. Unfortunately, I can't just hack in a quick fix, because it can affect other transformations as well. I'll look into that the next time I touch the transformation code.


Regards,
Oliver

-- 
Oliver Tonnhofer <olt at omniscale.de>
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