Ray tracing

[Olivier Tournaire]

Thank you Martin for your quick answer !

---------- Forwarded message ----------
From: Martin Schreiber <schreiberx at googlemail.com>
Date: 2009/2/20
Subject: Re: Ray tracing
To: Olivier Tournaire <olitour at gmail.com>
Cc: libkdtree-devel at lists.alioth.debian.org


hi olivier!

i think that libkdtree is not the thing you are searching for because it
operates point-wise only. it's possible to improve the intersection with
kdtrees but it's not as good as other methods. there's no explicit
method for ray intersection within a kdtree.

to compute an efficient ray intersection with triangles, usually a bsp
trees or octtree is used:
http://en.wikipedia.org/wiki/Binary_space_partitioning
http://en.wikipedia.org/wiki/Octtree

i used octtrees by myself because it's quite easy to implement it
(building up the octtree) as well as computing the intersections with
the cells.

OK, that seems to be a good choice ;-) Do you have a pointer to a good C++
implementation ? Or, are you willing to share some code, as I do not want to
reinvent the wheel ...

Best regards,

Olivier


feel free to ask further questions or correct me if i misunderstood you.

greez,
 martin




On Fri, 2009-02-20 at 17:39 +0100, Olivier Tournaire wrote:
> Hi all,
>
> I recently discovered libkdtree++ and it seems to be really
> interesting. However, before using it in one of my project, I need a
> few questions and I hope you could help me.
> I need to index triangles for fast intersection with rays computing.
> So, I think I have to write two classes, one for 3d points, another
> for 3d triangles which contains 3 points  as members. First question:
> which operators do I have to define in order to buil a kdtree to index
> my triangles ? Next, how do I instanciate the KDTree class ?
> Then, I would like to know, once the kdtree is built, which cells are
> intersected by a given 3d ray. How can I achieve this ? Last, once I
> know which cells the ray goes through, I would like to access the
> triangles contained in. Any tip ?
>
> Hope I am clear enough to get some help ...
>
> Best regards,
>
> Olivier
>
> --
> Olivier Tournaire
> MATIS - Institut Géographique National
> 73, Ave de Paris
> 94165 St Mandé cedex, France
>
> tel: (+33) 1 43 98 80 00 - 71 25
> fax: (+33) 1 43 98 85 81
> _______________________________________________
> libkdtree-devel mailing list
> libkdtree-devel at lists.alioth.debian.org
> http://lists.alioth.debian.org/mailman/listinfo/libkdtree-devel




-- 
Olivier Tournaire
MATIS - Institut Géographique National
73, Ave de Paris
94165 St Mandé cedex, France

tel: (+33) 1 43 98 80 00 - 71 25
fax: (+33) 1 43 98 85 81
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