From: PStuetz++at++esg.de
Date: 08/28/2002 04:28:23
Dear all,
we would like to make a Vissim-Performer application for a flight
simulator. It should cover a considerable large gaming area (10x10 deg
lat/lon). Our questions are:
1. How are the coordinates of the database vertices represented best? What
is common for such large scale applications:
- geocentric (lat,lon,alt) (only one referece point)
- cartesian (x,y,z) (earth-centred reference point)
- cartesian (x,y,z) (one local reference point, might be far away)
- cartesian (x,y,z) (various reference points, maybe for each tile to be
paged)
2. What is the best practise for positioning in the selected database, in
order to avoid numerical problems and angular/positioning errors?
We are aware, that different representation might cause distortions during
rendering (e.g. when the reference point is far away from the viewing
point).
We tried UTM representation with one local reference point resulting in
considerable angular distortions, when the viewing position was far away
(> 60 nm) from the refrence point.
We would like to use a geocentric database, but we do not know the proper
transformation for setting the viewpoint in performer without losing
numerical accuracy.
Thanks for your help.
Peter
/*DR.-ING. PETER STUETZ ESG Gmbh*/
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