[postgis-users] FOSS4G 2009 Videos

[Maxime van Noppen]

Rick wrote:
> WGS84 defines an ellipsoid that is used for a reference to approximate
> the shape of the earth.  If you are talking about a fictional planet,
> you can use anything, a sphere.
> 
> A real planet, at least one that is out of round enough, and with data
> good enough, for the data available to be in error, will have to have
> it's own ellipsoid defined.  (A sphere would probably do for most of
> these for some time to come as well)

Hmmm, ok.

> Your problem would be the radius, unless all your planets are the same
> size.  But you could do a scaling fixup fairly easily (I believe) to
> server your purposes.

They have different radiuses indeed. I'll investigate a bit more the
question. When we made our technical choices more than a year ago
PostGIS/Geos didn't seem to be as comfortable with spheric coordinates
than with plain cartesian ones. For example this post :

http://lin-ear-th-inking.blogspot.com/2007/09/geodetic-data-in-postgis-spherical.html

-- 
Maxime