Search found 51 matches

by szellmann
Thu Jun 25, 2015 11:38 am
Forum: General Development
Topic: Ideas request for a specific raytracing application
Replies: 28
Views: 17104

Re: Ideas request for a specific raytracing application

I build an orthonormal basis with the normal being an axis - the cosine_sample_hemisphere() function (which just happens to be already there) assumes that the hemisphere is above the x/z plane. PBRT guys do it similarly (I believe), but doing it in object space would also be ok. But this I also wro...
by szellmann
Thu Jun 25, 2015 11:29 am
Forum: General Development
Topic: Ideas request for a specific raytracing application
Replies: 28
Views: 17104

Re: Ideas request for a specific raytracing application

Why are you calculate a direction vector with w,u,v ? why not just use the normal (as direction) and the hit point to trace the hemisphere? I build an orthonormal basis with the normal being an axis - the cosine_sample_hemisphere() function (which just happens to be already there) assumes that the ...
by szellmann
Thu Jun 25, 2015 10:37 am
Forum: General Development
Topic: Ideas request for a specific raytracing application
Replies: 28
Views: 17104

Re: Ideas request for a specific raytracing application

Out of interest, I just compiled a very simplistic ray trace'd AO example. Wanted to try this, anyway :) If you'd like to you can play around with it: https://github.com/szellmann/visionaray/tree/master/src/examples I use an SSE 4.1 binned SAH BVH. You can try .obj models (1st cmd line argument). Ep...
by szellmann
Thu Jun 25, 2015 8:52 am
Forum: General Development
Topic: Ideas request for a specific raytracing application
Replies: 28
Views: 17104

Re: Ideas request for a specific raytracing application

Ray traced AO should be doable in real-time - 32 ray queries may probably suffice. You'll benefit from anyhit (rather than closest), and the memory accesses will also be (cache) friendly (because occluders will be clustered). I experimented with SSAO a few years ago (just for the fun of it) - I foun...
by szellmann
Thu Jun 25, 2015 6:12 am
Forum: General Development
Topic: Ideas request for a specific raytracing application
Replies: 28
Views: 17104

Re: Ideas request for a specific raytracing application

Some of the technical layers, are compositions (CSG) of other layers (subtraction) (adds tesselation complexity == +triangles) Independent of shading, but if you can make sure all primitives can somehow be described by quadrics, you can just do away with tesselation completely and ray trace the CSG...
by szellmann
Wed Jun 10, 2015 8:17 pm
Forum: General Development
Topic: Float versus double
Replies: 12
Views: 13002

Re: Float versus double

Being able to switch this, e.g. using a typedef at a global scope, may in general be a good idea. That said, I never experienced precision issues that rectified using double, I could always work around them, e.g. using an additional Newton-Raphson step for sqrt(), etc. With lots of matrix mults, may...
by szellmann
Thu May 28, 2015 8:56 am
Forum: General Development
Topic: CPU (real time) raytracing references and articles?
Replies: 8
Views: 7036

Re: CPU (real time) raytracing references and articles?

Well, I guess a dual socket 16 core Xeon E5-2680 is far more expansive than a single GTX Titan (even including the price of some kind of host CPU). Right, and to be fair one would actually have to compare with two Titans. It's only that I cannot confirm the 10x plus speedups you see on some GPU ven...
by szellmann
Wed May 27, 2015 1:52 pm
Forum: General Development
Topic: CPU (real time) raytracing references and articles?
Replies: 8
Views: 7036

Re: CPU (real time) raytracing references and articles?

I do not agree that GPU ray tracing can (in general) outperform the CPU by orders of magnitude. At least not, if the scene geometry doesn't entirely fit into the caches of the GPU's streaming multiprocessors. With Visionaray ( https://github.com/szellmann/visionaray ) you can run the same C++ ray tr...
by szellmann
Sat Mar 21, 2015 12:47 pm
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 24061

Visionaray Ray Tracing Framework

Hi there, I'd like to take this opportunity to advertise Visionaray, which is (yet another) ray tracing framework. https://github.com/szellmann/visionaray https://github.com/szellmann/visionaray/wiki Visionaray is based on generic programming with C++. In contrast to other frameworks, its main goal ...
by szellmann
Wed Jan 07, 2015 11:40 am
Forum: General Development
Topic: mrays/s
Replies: 4
Views: 4162

Re: mrays/s

So you basically find the metric impractical but for the "local" case. Those slides (https://software.intel.com/sites/default/files/managed/b8/3f/Embree_pt_1_Building_Ray_Tracing_apps_woop.pdf) e.g. compare Embree and OptiX based on mrays/s. I wonder how much faith one should put in those ...

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