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

Adrian Egli 3dhelp at gmail.com
Wed Oct 3 02:13:16 PDT 2007


Hi

there are many nice project and on going project for real time ray tracing.
i would say in the future there will be many more, because
the ray tracing becomes faster and faster. The future will be a hybrid
visualisation systems: GPU / CPU and also OpenGL / RayTracing.

Even for OSG it will become a challenge to follow such latest development
and such latest ideas, but the core concept of all such systems are quite
similar.
All systems needs a spatial data structure. In OSG the objects are organised
in bounding sphere hierarchy. And unfortunately the
primitives are just in arrays, what is may fast for rendering but for
intersection testing, tracing it's a known poor data organisation.

(Robert) What are you thinking about this topic, just as a short general
idea. What danger do you see if we would implement a spatial hierarchic data
structure (kd-tree) to replace the array based vertex, triangles storing.
what can be a challenge or what would be quite hard to change, and where are
unknown dangers w.r.t performance for face rendering (OpenGL) ?

/adegli

2007/10/2, Abe Stephens <abe at sci.utah.edu>:
>
>
> I'm not aware of any open source interactive ray tracers that
> vivaciously support third-party scene graphs like OSG.
>
> OpenRT (not open source) has been demoed at the Mercury booth @
> siggraph running off a scene graph (possibly OpenInventor (?)). Razor
> (not open source) is an IRT system from UT Austin which is tightly
> integrated with its own scene graph (supports collada). We've had
> some traffic on the Manta (open source) mailing list about scene
> graph integration. The projects were all outside of Utah so I'm not
> sure if they targeted a standard tool like OSG.
>
> Abe
>
>
> On Oct 2, 2007, at 4:26 AM, osg-users-
> request at lists.openscenegraph.org wrote:
>
> > Message: 24
> > Date: Tue, 2 Oct 2007 12:25:58 +0200
> > From: " Tobias M?nch " <muench.tobias at googlemail.com>
> > Subject: Re: [osg-users] Searcing for raytracer implementation based
> >       on OSG
> > To: "OpenSceneGraph Users" <osg-users at lists.openscenegraph.org>
> > Message-ID:
> >       <f90040970710020325s44d43a11m799458b0db13458f at mail.gmail.com>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Hello Adrian
> >
> > If I get you right, you think that the OSG data representation is not
> > optimized for use within a raytracer application. So it will be
> > possible to
> > code a raytracer with OSG but results won't be very efficient and
> > powerful?
> >
> > regards, Tobias
> >
> > On 10/2/07, Adrian Egli <3dhelp at gmail.com> wrote:
> >>
> >> Hi Tobias,
> >>
> >> Greate would be to get a RayTracer attached to the OSG scene. With
> >> option
> >> to trace or not. Normally OSG won't trace, but if we like to get high
> >> quality screens, we can just turn on the tracing. But i was
> >> thinking about
> >> this still more then once. What we should get or what i like to
> >> integrate as
> >> soon as i have some hours to analyse the osg core, we should store
> >> the
> >> triangles, trianglesfan, ... (GL geometries) in a accelerated
> >> spatial data
> >> structure, best kd-Tree like data organisation. Even the
> >> intersection test
> >> could be boosted, also futures animations, collision checks and so
> >> on,
> >> boosting of depth sorting for transparency pre triangles should
> >> become
> >> possible.  Also haptic-rendering could be an option for future
> >> application.
> >> This integration would be an essential topic.
> >>
> >> 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.
> >>
> >> and the once we have a fast internal data representation, we may are
> >> really close to render the scene no longer as face rendering also ray
> >> casted, ray traced parts would be an futur options. what would be
> >> really
> >> greate. May we will get small parts raytraced, others not.
> >>
> >> what are others thinking about this topic.
> >>
> >> /Adegli
> >>
> >> 2007/10/2, Tobias M?nch <muench.tobias at googlemail.com>:
> >>>
> >>> Hello to all OSG developers.
> >>>
> >>> Does anybody has developed a raytracer based on OSG or OpenGL
> >>> which is
> >>> free to use on other applications? It is important for me that no
> >>> changes
> >>> are necessary to the OSG-framework like the raytracer of Amit Ben-
> >>> David, who
> >>> modified the osg:Vec3f class. I need it for my thesis and
> >>> unfortunately I
> >>> have not enough time to code one by my own.
> >>>
> >>> best regards, Tobias
> >>>
> >>> p.s.: The source of Ben-Davids raytracer: http://
> >>> www.cs.technion.ac.il/~cs234326/projects/GLSLRayTracer/main.htm
> >>>
> >>> <http://www.cs.technion.ac.il/%7Ecs234326/projects/GLSLRayTracer/
> >>> main.htm>
> >>>
> >>> _______________________________________________
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> >>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-
> >>> openscenegraph.org
> >>>
> >>>
> >>>
> >>
> >>
> >> --
> >> ********************************************
> >> Adrian Egli
> >> _______________________________________________
> >> osg-users mailing list
> >> osg-users at lists.openscenegraph.org
> >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-
> >> openscenegraph.org
> >>
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-- 
********************************************
Adrian Egli
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