[Source] [X3D-Earth] Xj3D property setting for origin manager, for inclusion in X3D-Edit

[chris]

thanks Rex, yeah that all makes sense, just one more query on the last
point:


2009/6/6 Rex Melton <rex.melton at comcast.net>
....


> A straight line calculation certainly is more efficient than the
> orthodromic distance. However, the elevation threshold is set rather high by
> default (50km) for a variety of reasons. A straight line distance from the
> established origin to the viewpoint would incorporate the elevation. Adding
> that component to the distance threshold would cause recalculations more
> frequently than would really be necessary. In other words, in order to keep
> the amount of recalculation down, only the 'lateral' distance from an
> establish origin is considered (and necessary I think) and not the vertical.
> Hope that makes sense..... If not, let me know and I'll try to explain it
> again.


So if you make the threshold distance greater, you could use the more
efficient calculation, e.g. comparing distance^2 to threshold^2? I remember
that geovrml scaled speed based on elevation, so one could also scale
threshold similarly.
Presumably, the content developer could also tweek the distance based on
amount of jitter and framerate.

Chris



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