Re: Positional Accuracy

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John Rohlf (jrohlf++at++tubes)
Fri, 22 Sep 95 10:44:51 PDT

>
> We are flying around a relatively large database that was created from
> DTED data. The database has been translated to its correct lat lon position.
> The problem we have is the X,Y,Z numbers are so large, the image seems
> to jitter eventhough the eyepoint is stationary. I would appreciate any
> existing solutions or workarounds.
>

        A solution is to chop up the database into tiles
whose extent is adequately represented by a float. Recompute the coordinates
of each tile based on an origin at the tile center and parent each
tile with a pfDCS. Determine which tile the viewer is in and compute
view position relative to the origin of the tile. Set the viewer's tile
DCS to the identity matrix and translate all other tiles relative to the
viewer's tile. This should give you good precision and performance but
will complicate computations which cross tile boundaries, e.g. - intersections.

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