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From Wes Gilster <>
Subject Re: Applicability of PolyhedronsSet for high polygon counts
Date Sun, 06 Nov 2016 03:40:10 GMT
I really appreciate the quick response. Even though I believe this API 
has the functionality I need, I'm not really sure I can easily tune the 
performance. I need to check out a few other APIs to determine if they 
will be a better fit, and if I can't find anything that fits, I'll 
probably see what I can do with this geom package. Thanks again for 
being so upfront about the state of the project.


Wes G.

On 11/5/2016 11:03 AM, Gilles wrote:
> Hello.
> On Fri, 4 Nov 2016 23:57:48 -0500, Wes Gilster wrote:
>> I've been using the commons math geometry libraries for some simple
>> 2d intersection functions, but I'm now interested in expanding it's
>> use to include some manipulation of 3d models with polygon counts that
>> will easily reach 200,000 tris. More specifically I would like to
>> build physical support structures in 3d models. Given that commons
>> math geo libraries used BSP trees, I had assumed the performance would
>> be quite adequate. However I'm having second thoughts as to whether
>> this is the right API for this modeling. I'm building models from STL
>> files with this constructor:
>> org.apache.commons.math3.geometry.euclidean.threed.PolyhedronsSet.PolyhedronsSet(List<Vector3D>,

>> List<int[]>, double)
>> It seems there are some quite in-efficient loops in here, and with
>> models with high polygon counts this function really performs poorly:
>> org.apache.commons.math3.geometry.euclidean.threed.PolyhedronsSet.buildBoundary(List<Vector3D>,

>> List<int[]>, double)
>> It also seems as though this API is going to be quite intolerant of
>> imperfect geometry.
>> Below is an example that loads an STL from disk and inserts into this
>> the PolyhedronsSet:

>> I'm hoping someone with a bit of experience in this API could confirm
>> this assessment.
> I have no good news; there is probably no one listening here who
> has more experience than you on using this part of the Commons
> Math library.
> Many of the more advanced codes (in size and/or complexity) have
> been orphaned by a fork last May.
> A lot of discussion has arisen about the future of CM (have a look
> at the ML archive if you are interested).
> Some parts have found new maintainers.
> We should certainly welcome people who have expertise with using the
> "geometry" package, to improve and maintain it, and eventually
> release it as a standalone component.
> Best regards,
> Gilles
>> Thanks,
>> Wes G.
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