[GRASS5] [bug #2144] (grass) m.proj2 returns wrong answer if you use proj=longlat

Paul Kelly via RT grass-bugs at intevation.de
Wed Oct 8 06:31:48 EDT 2003


guest wrote (Wed, Oct 1 2003 12:50:26):

> Subject: m.proj2 returns wrong answer if you use proj=longlat
> 
[...]
> 
> (same if you use proj=latlong)
> 
> 
> 
> but works correctly if you use proj=ll:
> 
[...]
> 
> I'm a bit confused as to whether the parameters should be proj ones or 
GRASS ones.

It should be the GRASS names for everything (if you insist on using 
m.proj ;) ). GRASS used proj=ll back in the early '90s when the standard proj 
did not allow use a 'pseudo-projection' of lat/long and everything had to be 
treated as either a forward or inverse projection from/to lat/long. When 
Frank made his improvements he chose to use proj=latlong or proj=longlat, so 
the GRASS 'proj=ll' was left as an historical oddity. As far as I can make 
out anyway that is what has happened.

> 
> note: specifiying datum in one set of parameters but not the other is buggy.
> 

Is this PROJ bug 368? ( http://bugzilla.remotesensing.org/show_bug.cgi?
id=368 ) I have applied a fix to the internal PROJ in the GRASS CVS that 
should fix this...could you maybe try that (compile 5.3 --with-proj=no)

Paul


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