[postgis-devel] Geodetic issues

[Paragon Corporation]

For what it's worth Chris -- it uses the 

_BestSRID functions (_st_bestsrid(geography, geography) ,
_st_bestsrid(geography) to arrive at best SRID for both geometries  then the
rest is just plain transformation.

I think at the Poles it uses stereographic something or other.

Paul can correct me if I misspoke.





Thanks,
Regina 

> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net 
> [mailto:postgis-devel-bounces at postgis.refractions.net] On 
> Behalf Of Chris Hodgson
> Sent: Thursday, September 01, 2011 4:36 PM
> To: PostGIS Development Discussion
> Subject: Re: [postgis-devel] Geodetic issues
> 
> Thanks Bryce, I do believe you're right.  However that 
> doesn't explain this problem:
> 
> http://trac.osgeo.org/postgis/ticket/1170
> 
> I'll look a bit deeper.
> 
> Chris
> 
> Bryce L Nordgren wrote:
> >
> >
> > On Thu, Sep 1, 2011 at 7:26 PM, Paul Ramsey <pramsey at opengeo.org 
> > <mailto:pramsey at opengeo.org>> wrote:
> >
> >
> >     > - Is it illegal to have a point on the poles? From
> >     ptarray_check_geodetic()
> >     > in /liblwgeom/lwgeodetic.c
> >     >
> >     > if ( pt.x < -180.0 || pt.y < -90.0 || pt.x > 180.0 || pt.y >
> >     90.0 ) return
> >     > LW_FALSE;
> >     >
> >     > It seems kind wierd that it is ok to have a polygon the
> >     circumnavigates the
> >     > pole, but not a point on the pole?
> >
> >     It is weird, and I cannot access my last year self to 
> figure out WTF I
> >     was thinking doing strict less-than rather than 
> less-than-equals. I
> >     think it's just going to have to change.
> >
> >
> > As I read it, that statement only returns false if y > 90.0 or y < 
> > -90.0; meaning that a point on the pole (exactly 90.0 or 
> -90.0) would 
> > return true. Ergo, the stmt as is permits points on the poles. Am I 
> > missing something?
> >  
> > Bryce
> > 
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