[R-sig-Geo] spatial projections

[James Stegen]

Hello,

I have lat-long coordinates for a bunch of localities spread across 
multiple hemispheres, which also extend into high latitudes.
What I would like to do is re-project the lat long coordinates into a 
projection that gives me spatial positions in km from some arbitrary point.
The key is that I would like the distances among communities to be 
maintained. Specifically, if I calculate a distance matrix using lat 
longs in the
great circle equation, I would like a distance matrix calculated from 
the reprojected positions to give the same distances.
I haven't found a projection that can do this. Using the orthographic 
projection, for example, leads to larger distances among sites that 
occur at high latitudes,
relative to the distances provided by the great circle equation. I also 
need to know actual spatial positions in both axes, not just overall 
distance, relative to
an arbitrary point on earth.

Many Thanks,
James Stegen

-- 
James C. Stegen
NSF Postdoctoral Fellow in Bioinformatics
University of North Carolina
Chapel Hill, NC
919-962-8795
stegen at email.unc.edu