[postgis-devel] Geodetic issues

[Chris Hodgson]

Paul, I think these questions are primarily for you - in light of a few 
recent bug reports, I'm trying to figure out what is going in in 
geography land (I apologize for being blissfully ignorant of much of the 
work done so far).

- 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?


- Am I right to think that the current "grumpy faces" in the function 
support matrix:

http://postgis.refractions.net/documentation/manual-svn/PostGIS_Special_Functions_Index.html#PostGIS_TypeFunctionMatrix

Are pretty big hacks that have no hope for any kind of polar-encircling 
data or other globe-wrapping data like for example satellite swaths? And 
really the only way around these issues, which also could end up 
addressing everything from isvalid to union is to write a geodetic-aware 
equivalent to GEOS (or make JTS/GEOS "geodetic aware")?  Are there any 
plans for moving forward with something like that? I recognize there 
would be a large amount of work involved (probably more than writing JTS 
or GEOS as is, for planar geometries?). Is this the direction we would 
want to go? Or am I wrong and these aren't big hacks but are "the way to 
do it" and just need further tweaking to handle the ugly cases?

Thanks,
Chris