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At 10:28 AM 9/27/04 -0400, Charles Seitz   wrote:



>Obviously, the next step would be to rewrite the software to accept data
>from additional sightings and calculate the circle intersections.
>That's easier said than done.  Many hours of web searching have failed
>to reveal any equations to do this.  I can't believe that during several
>thousand years of spherical geometry study, someone has not solved this
>problem.  It might be a horrendous problem but the solution is out there
>somewhere.  GPS is based on a similar concept.
>
>I'm not a mathematician and will not attempt to derive the equations.
>I'll look into solving this problem numerically.  But, that is a brute
>force approach that is not particularly satisfying from an aesthetic
>viewpoint.

I conducted a similar search some years ago without much success so I sat
down and figured it out.
The biggest problem is paying due regard to the quadrant of the results of
the various arc whatever functions.
If you like, I could send you a short paper outlining the procedure.  I
don't think I can post it to the list since
it contains some figures.  I also have a windows application that will
compute the equal altitude circle
intersections and optionally display the circles on a world map.

Mike Dorl

   

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