[postgis-users] Is the Earth round??

[Brent Wood]

--- "Gregory S. Williamson" <gsw at globexplorer.com> wrote:

> Having recently crossed paths with this for certain vector data, I am
> wondering if there are any guides that might indicate pros/cons of such
> projections ? Or is this a topic of some undergraduate class ?
> 
> Thanks for any illumination on this geomancy...
> 

Based in New Zealand, & working with lot's of lat/long data, I find PostGIS &
proj4 work fine with longitudes stored as 0-360 instead of the more
conventional +-180. (so -170 = 170W => 190) We also use a custom offset
mercator projection, which also moves the problem out of our locality. You may
find some other projection will work for you, but there pretty much always
seems to be a discontinuity somewhere.

So it is still cartesian, but moves the problem around to 0deg long instead of
180.

GMT (Generic Mapping Tools) is the only package I've found which comes close to
having a working spherical data model, where pretty much -360=0=360=720....

We are looking at moving away from ArcIMS for some projects coz it can't manage
 a clean 180 degree solution. May be using mapserver/Postgis/proj4 to replace
it.


Cheers,

  Brent Wood