[MetaCRS] Inf in projection results

[Martin Desruisseaux]

Le 24/05/11 19:36, Paul Ramsey a écrit :
> And following on with a non-projection-related query: if you as a
> geometry processing routine got handed a geometry with Inf
> coordinates, what would you do? Give up? Coerce them into something
> else?

I would suggest to keep the infinite values. IEEE arithmetic usually do the 
right thing with infinities (x/Inf = 0 if x!=Inf, etc.), and Java Math functions 
are properly defined (atan(Inf) = 90°, etc.).

In Geotoolkit.org, we have allowed Map Projection to returns infinite values 
(e.g. 90°N in a Mercator projection = Infinity, and ensuring that the conversion 
back to EPSG:4326 give 90°N). In my point of view this actually make the 
handling of geometries easier. By removing as much special cases of the like "if 
(x < threshold)" as possible (which were used in order to avoid divisions by 
zero in the legacy GeoTools referencing code), users have reported that the 
reprojections were smoother.

Regards,

     Martin