[GRASSLIST:1444] Bug in s.proj?

[David Orme]

Hi,

I e-mailed yesterday about a mismatch between Arcmap and Grass 5.0.2 
transformations of sites from a global cylindrical equal area location 
to a geographic. I've been playing around some more and it looks to me 
as if either:

1) s.proj has a bug in it,
2) arcmap has a bug in the transformation of sites or,
3) I've missed something elementary.

I created a point shapefile in arcmap of the centre points of the grid 
cells for the CEA location and read this into grass using s.in.shape. 
I've checked that the values in the sites file are what I was 
expecting. I used s.proj to project these sites into a geographic 
(wgs84) location. I also used arcmap to project the original behrmann 
points shapefile into wgs84 and then imported this into my grass wgs84 
location using s.in.shape. The two sets of sites are not in the same 
place - in extreme latitudes the discrepancy is about half a degree. I 
won't attach the files to preserve bandwidth but if anyone wants them, 
let me know.

Any suggestions?

David

---------------------------------------
Dr. David Orme

Department of Biological Sciences
Imperial College London
Silwood Park Campus
Ascot, Berkshire SL5 7PY UK.

Tel: +44 (0)20 759 42358
Fax: +44 (0)20 759 42339
e-mail: d.orme at imperial.ac.uk
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