Msg: 7028 *Conference*

03-28-97 19:06:59

From: RON WIESEN

To : TOM UPTON

Subj: SOL CENTRIC VIEW

No suggestions yet Tom. A few questions first. By "snapshots of relative
positions from Sol centric" it sounds like you're not going to use Right
Ascension/Declination/Distance coordinates to define the 3-D positions - so
what coordinate scheme will define the 3-D positions? Regarding rotation in two
planes (horiz & vert), that's only 2-D rotation - without a distance ordinate
for the third dimension, a "travelling view" isn't possible so where is the
merit?

Maybe by "snapshot" you mean a 2-D plane projection of limited scale, such as a
square projection limited to say 10 degrees by 10 degrees. Of course with 2-D
projection there's in inherent 180 degree by 180 degree limit and at this limit
2 "snapshot" projections are needed (front & rear) to cover all positions but
the ordinate at any 180 degree limit rises to infinity. Thus a limit less than
180 degrees (and consequently more than 2 "snapshots") is needed for practical
reason.

I know that it's a 2-D view that you're after because it must appear on the
M100 LCD (a 2-D rectangular plane). Is the view intended to have angular
accuracy (viewed at some refernce distance such as arm's length) or is Mercater
map type of distortion acceptable? The "horiz & vert" rotation you speak of: is
that synonomous with "left/right & up/down" relative to the M100 LCD? In other
words, where the user (maybe via arrow keys) "rotates the view" does he see on
the LCD what appears when you "turn your head" while observing the real stars
in the sky?