[MetaCRS] Inf in projection results

[Mikael Rittri]

Hello,

In Carmenta Engine, we use non-standard projection 
formulas where a world map would otherwise go to 
infinity. In this way, the entire world map of a 
projection is compressed into a finite area.  

Of course, coordinates that have been projected
with the non-standard formulas cannot be exchanged
with other GIS systems, but this matters only 
where the projections are very distorted anyway
(like near the poles for Mercator), so it should
not matter in practice. 

Regards,
Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com 

-----Original Message-----
From: metacrs-bounces at lists.osgeo.org [mailto:metacrs-bounces at lists.osgeo.org] On Behalf Of Paul Ramsey
Sent: den 24 maj 2011 19:37
To: metacrs at lists.osgeo.org
Subject: [MetaCRS] Inf in projection results

Hi All,

We've recently run into a problem with a transformation returning Inf coordinates... when passed further down the processing chain to GEOS, algorithms go into infinite loops. So question: should the possibility of getting back Inf results be something we should expect when running a proj4 transform (in this case it was going from a planar to 4326, so the Inf value was even more surprising to me)?

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?

P.
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