On Montag 30 Mai 2005 14:21, Jon Stockill wrote:
> I'm not certain the area that the ground cache covers, but I suspect it
> has applications beyond just contact points. ISTR Lee was wanting to
> know ground elevation a distance ahead of the aircraft for the terrain
> following mode of the TSR2s autopilot - could this be used?
Hmm, not really.
The problem that cache solves is the lookup time when doing queries for
altitude computations or in the future intersection tests with whatever (May
be crashes with power lines?).
If you do that test once for each timeframe and only at one place per
aircraft, you can well, and you even have to, traverse the whole scenegraph
to get that information.
The time to traverse the whole scenegraph is too high if you want to know that
information for many points and for different informations like the locations
for the wires on the carrier.
So the trick is to build a as small as possible subset of the scenegraph and
do queries there.
The smaller the cache is, the better are the response times.
So for that reason, I don't think that this is usable for this task at the
moment.
What you will need for that will be more something similar like the
groundcache covering a much bigger area.
But instead of putting every surface into that cache, one could preselect the
objects depending on the distance and its size, that is ignore too small
ones. And additionally, one should simplyfy the surfaces to some bigger ones
if they are far away.
A structure like that might recycle and/or share some code with the
groundcache.
And such a structure can probably be well used for an improoved implementation
of radar contacts.
That problem is a typical LOD algorithm, I expect to find magnitudes of
publications about such and fast algorithms.
Greetings
Mathias
--
Mathias Fr�hlich, email: [EMAIL PROTECTED]
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