wrote:
I'm working on a project of modeling the stars of the constellations in
3-D; not for their positions relative to Earth, but relative to any
given person being at 0,0,0.

Is there a simple formula for this? ...or better yet, do you know
anyone who has them on the net or in a book?

It's going to be very messy. Star positions practically BEG for
spherical coordinates, (which is what they are really), so converting to
Cartesian you are looking for trouble.

I don't know if anyone has been masochistic enough to try it, but you
could conceivably do it. Open any Calculus book and apply the conversion
formulas found there, although I suspect that you'd be better off if you
situated Earth's center at (0,0,0). That way, you avoid the problem of
those coordinates changing (even more slightly) everytime the season
changes and the observer's position changes on the surface of the Earth.

Since the celestial dome appears "spherical", be prepared to be
bombarded with thousands of sin's and cos's.

Good luck!

Thanks!

Rick.
--
I. N. G. --- http://users.forthnet.gr/ath/jgal/