Re: R-tree indexing

[BARTHOLDI Paul <Paul.Bartholdi@obs.unige.ch>]

Hello,

There is an other solution, which solves nicely the equator/polar singularity
etc, but introduces other problems.

Transform the (RA,DEC) into (x,y,z) on the sphere. 

There is then no polar singularity, and short distances/boxes are very
easy to work with. Great circle are also easy to define (use vector product
to define the vector perpandicular to the grea circle) and work with, and
so to measure long distances.

I have no idea how this would work under PostgreSQL indexing.

Best regards,     Paul