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4D and 5D bsptrees: source code anyone?
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SamPlay
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Question 4D and 5D bsptrees: source code anyone? - 26-10-2006

After looking on very a interesting academic paper ( a thesis I think) from Jiri Bittner dealing in particular with region-to-region visibility, it is clear to me that bsptrees of dimension higher than 3 are THE solution. But I do not how how to split a 4D or 5D polyhedron, and did not found anything useful on the net.
Did anyone already tackled the problem, or does someone know where I could find algorithms?
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Re: 4D and 5D bsptrees: source code anyone?
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mirv
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Default Re: 4D and 5D bsptrees: source code anyone? - 26-10-2006

I haven't really tackled region to region visibility in terms of creating something like a PVS for a bsp tree yet - though I have tackled overall hierarchical visibility culling (terrain mostly, and some brief looks at portal culling). I googled that paper, but it's early and I haven't eaten, so haven't really looked too closely at it.
First off: there's no "the" solution to anything - what's useful in one place may not be so in another, just something to keep in mind. Anyway, from what I gather that paper is mostly about line representations - and that's it, a representation. If you represent a polygon in 4D or 5D data sets, it's still a representation of 3D data, so maybe just split the polys in 3d space (plenty of stuff out there on that), and then convert the results to any specific 4d or 5d data representations.
What are you trying to do exactly? Build a PVS, or just occlusion information?


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Re: 4D and 5D bsptrees: source code anyone?
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@$3.1415rin
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Default Re: 4D and 5D bsptrees: source code anyone? - 26-10-2006

the bsp process should be the same for 5dimensional objects as for 3dimensional objects. although I have some problems imagining a 5dimensional volume, but in principle, there is nothing making the bsp. stuff restricted to 3dimensional worlds.

I havnt read that paper though, so I don't know exactly what 4 or 5d world you want to visualize. calculating relativistic effects is done another way anyway afaik


  
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Re: 4D and 5D bsptrees: source code anyone?
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SamPlay
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Default Re: 4D and 5D bsptrees: source code anyone? - 27-10-2006

I agree that there is no absolute solution. I just meant that compared to what I have seen on PVS computation( portal based ), the solution of J Bittner seems more efficient, and more robust( but I am not an expert!).

My interest is not in PVS computations, I am presently starting to think about whether an automatical map tactical analyzer is feasible. This means in particular knowing behind which face a bot can hide from potential enemies in neighbouring "regions". This is basically a problem of visibility/occlusion and that is why I looked first at PVS computations methods.

Besides, working with 4D is a way to address move issues of rotating hulls, by adding yaw( heading) to the 3 cartesian coordinates.

As regards Bsptree, I agree that the algorithm works in any dimension, but the splitting of a N-dim polyhedron is a problem to me.
Sort of going back to 3D does not work, as using Plucker representation of lines in 5D is the key ( and smart) thing in J Bittner solution.
Thanks for your comments!
NB: the title of Jiri Bittner's thesis is "Hierarchical Techniques for visibility computations"

Last edited by SamPlay; 27-10-2006 at 10:33..
  
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