Search found 51 matches

by szellmann
Mon Jun 20, 2016 2:35 pm
Forum: Visuals
Topic: Glitch Pictures anyone?
Replies: 81
Views: 109852

Re: Glitch Pictures anyone?

https://youtu.be/DrEkr1PJIDs

Glitch starts at sec. 14 where the path tracer tries to converge while the scene data changes. Found this "effect" especially interesting with the animation moving this particular way.
by szellmann
Mon Jun 06, 2016 9:35 am
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 25950

Re: Visionaray Ray Tracing Framework

Visionaray now supports multi-hit ray/object traversal. Check out the example program: https://youtu.be/wv8ZkVoHtDw https://github.com/szellmann/visionaray/wiki/More-examples https://github.com/szellmann/visionaray/tree/master/src/examples/multi_hit The multi-hit feature is of course not restricted ...
by szellmann
Thu Mar 17, 2016 11:11 am
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 25950

Re: Visionaray Ray Tracing Framework

Take a look at the new Visionaray multi-volume rendering example: https://youtu.be/aMRb3LJzgXs https://github.com/szellmann/visionaray/tree/master/src/examples/multi_volume https://github.com/szellmann/visionaray/wiki/More-examples The example program shows a more complex kernel - "SciVis" direct vo...
by szellmann
Thu Oct 29, 2015 8:14 am
Forum: General Development
Topic: Basic question: material that will change the normal
Replies: 3
Views: 7393

Re: Basic question: material that will change the normal

You should keep a copy of the surface real geometric normal along side and use that to displace the starting position of rays to avoid self-intersection. Keeping the geometry normal around is good advice in general, because that's the one you need to determine if you process a "back-face" or a "fro...
by szellmann
Wed Oct 21, 2015 1:09 pm
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 25950

Re: Visionaray Ray Tracing Framework

Some more shameless self-promotion :) I wanted to post some progress from the virtual reality front. Here's some shots where you can see (with your red-cyan glasses :) ) how distracting noise from not converged, naive path tracing really is in VR. Problem in VR is that the user moves his/her head al...
by szellmann
Tue Oct 13, 2015 10:28 am
Forum: General Development
Topic: GPU style shaders in raytracing
Replies: 1
Views: 3843

Re: GPU style shaders in raytracing

SSAO is computed in a fragment shader. You will have to pass a depth buffer texture to the shader. A depth buffer is fairly simple to generate as a ray tracing result, you basically just store first hit positions in world/object space and later transform them to OpenGL window coordinates. I wouldn't...
by szellmann
Mon Oct 05, 2015 9:03 am
Forum: General Development
Topic: Separate GPU compute kernels vs. a single GPU kernel
Replies: 10
Views: 10373

Re: Separate GPU compute kernels vs. a single GPU kernel

Just came across this very interesting paper: https://mediatech.aalto.fi/~samuli/publications/laine2013hpg_paper.pdf The authors basically just confirm the advice you people here gave me. Seems like I have to do further testing with more complex materials and/or multiple materials, and eventually pr...
by szellmann
Thu Oct 01, 2015 9:24 am
Forum: General Development
Topic: Separate GPU compute kernels vs. a single GPU kernel
Replies: 10
Views: 10373

Re: Separate GPU compute kernels vs. a single GPU kernel

Hi papaboo, thanks for your answer and for sharing the experience - yes, what you say sounds reasonable: identify the sources of register pressure, and separate kernels if two independent tasks use a lot of registers. I analyzed register usage for the ray generation kernel, it's ~20 registers (I use...
by szellmann
Wed Sep 30, 2015 8:43 pm
Forum: General Development
Topic: Separate GPU compute kernels vs. a single GPU kernel
Replies: 10
Views: 10373

Re: Separate GPU compute kernels vs. a single GPU kernel

I'm interested in this. What is the data layout of intermediate buffers of your experiments, SoA or AoS? GPU has very limited size of cache per thread compared to CPU, so data layout seems to strongly influence the performance. Uh, you're right, I haven't given this enough thought. Data layout for ...
by szellmann
Wed Sep 30, 2015 2:35 pm
Forum: General Development
Topic: Separate GPU compute kernels vs. a single GPU kernel
Replies: 10
Views: 10373

Re: Separate GPU compute kernels vs. a single GPU kernel

Opinions still differ on this topic. As an example, Chaos Group is not (yet?) convinced and chose a different way of speeding up their megakernel: http://dl.acm.org/citation.cfm?id=2668941 Thx, didn't know that paper! iray on the other hand uses wavefront successfully (see for example http://on-dem...