[postgis-users] 2D point from 3D

[Eli Dylan Lorimer]

Hi,
Quick thanks to James Marca and Craig Miller whom answered my last  
question!
I was wondering how I would best go about obtaining a 2D point (x,y)  
from a 3D point (x,y,z). Must I go through 2 conversions using WKT?  
I'm asking as I'm still slightly wary about the best model to use in  
order to store GPS waypoints and ultimately view 2D+T trajectories  
using java3D. If I store x,y as a 2D point object, I could then  
store  time and elevation (which I may never use) as attributes but  
then I was thinking that it might behoove me to store elevation as  
the z in a 3D Point object. If I did that though, I'd have to ignore  
it for most of my calculations involving clustering and whatnot as I  
*currently* have no use for elevation and in fact must use time as my  
z in all my calculations. Hope that made sense. Any last thoughts  
before I commit to a model? Much appreciated.
./dylan