[osg-users] Searcing for raytracer implementation based on OSG

Adrian Egli 3dhelp at gmail.com
Tue Oct 2 07:50:34 PDT 2007

Hi Sébastien,

as starting point we should think about only static scenes, not morphable
objects. And for speed up line intersection tests
we may can append a kd-tree or at least a spatial datastructure. i am sure
that then your ray tracer would be faster than 20k.
Event for motion model using intersection tests (terrain, model, ...)
becomes faster, i had once a model with 100k triangles
in the same geometry and the osg fps drops unter a usable limit. then i
start looking for the issue and i believe now, that this was
of the linear in time intersection test. after removing the intersection
test, the frame was greate. the bootle neck was  located.


2007/10/2, Jean-Sébastien Guay <jean-sebastien.guay at polymtl.ca>:
> Hello Adrian,
> > I am not yet sure how we should change the osg internal data structure,
> at
> > the moment we store vertices in simple arrays. I feel like to remap them
> > into an kd-tree. then the whole scenegraph is organised in a spatial
> data
> > structure.
> I agree, something like that would be great. If the goal is just to be
> able to take a raytraced screenshot, a kd-tree might be workable, but
> if we want to try and get some kind of realtime or quasi-realtime
> raytracing going, we'll need something we can rebuild faster than a
> kd-tree, or perhaps a kd-tree for anything tagged as STATIC and a BVH
> for anything tagged as DYNAMIC...
> I've done some raytracing with OSG but I don't have time to implement
> anything like that - my thesis is due "as soon as possible" :-)  So I
> just used osgUtil::LineSegmentIntersector out of the box, and as you
> might guess the speed is not that great. In a simple scene I get only
> about 20k ray/triangle intersections per second.
> If there was real interest in something like this, I would be glad to
> help with the implementation, but as I see it, it will only be used in
> very few cases...
> J-S
> --
> ______________________________________________________
> Jean-Sebastien Guay     jean-sebastien.guay at polymtl.ca
>                          http://whitestar02.webhop.org/
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Adrian Egli
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