Search found 46 matches

by szellmann
Mon Dec 04, 2017 10:54 pm
Forum: General Development
Topic: Why is volumetric emission proportional to absorption coefficient?
Replies: 5
Views: 362

Re: Why is volumetric emission proportional to absorption coefficient?

I think it is required that emitting particles should not scatter light I'm not quite sure if I understand how you come to this assumption and if I totally understand your question, but I don't see why particles that emit light shouldn't also scatter light. However, the mental model behind radiance...
by szellmann
Tue Nov 28, 2017 9:17 pm
Forum: General Development
Topic: Why is volumetric emission proportional to absorption coefficient?
Replies: 5
Views: 362

Re: Why is volumetric emission proportional to absorption coefficient?

I don't quite understand the question: doesn't the first term refer to a particle density at an integration position x that emits radiance L_e in viewing direction w, and that the particle density absorbs radiance by w.r.t. sigma_a(x)? The emitted radiance is not proportional to the absorption, but ...
by szellmann
Wed Jun 21, 2017 1:48 pm
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 19751

Re: Visionaray Ray Tracing Framework

Here's the (extended) AO results from the SEARIS paper (https://szellmann.github.io), along with a script to run the benchmark. Results for interesting platforms (CPU,GPU) not listed yet are highly welcome!
by szellmann
Thu Mar 16, 2017 10:40 am
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 19751

Re: Visionaray Ray Tracing Framework

Going to talk about Visionaray at SEARIS (http://www.searis.net), which is a workshop colocated with IEEE VR.

Check out this teaser video: https://youtu.be/bhhwEO4KWII
by szellmann
Fri Jan 20, 2017 9:10 pm
Forum: General Development
Topic: Intersection of ray with quadric surface for hobby ray tracer
Replies: 6
Views: 2984

Re: Intersection of ray with quadric surface for hobby ray tracer

Here's an explanation of how to build up the 4x4 matrix for several quadric types: https://www.siggraph.org/education/materials/HyperGraph/raytrace/rtinter4.htm I believe that Glassner's 1980's book "Introduction to Ray Tracing" also has a paragraph on this. There's a ray/quadric implement...
by szellmann
Fri Dec 30, 2016 1:05 am
Forum: Tools, Demos & Sources
Topic: Visionaray Ray Tracing Framework
Replies: 11
Views: 19751

Re: Visionaray Ray Tracing Framework

It's christmas holidays, and so I had a little fun compiling Visionaray for my new Raspberry PI 3: https://youtu.be/7bJTEmdlT2Y I haven't done anything special but applying some tiny compile fixes for this architecture, so there's no optimizations yet. I'm just porting the SIMD math lib to ARM NEON....
by szellmann
Mon Dec 12, 2016 3:46 pm
Forum: General Development
Topic: Multiple Textures CUDA/OpenCL
Replies: 8
Views: 9741

Re: Multiple Textures CUDA/OpenCL

I used tiles/bricks, used morton curves and my texturing functions also support SoA access w/ SSE and AVX. Of course the outcome of the tests depends on overall coherence. Baseline was that linear filtering had a significant impact when texturing was emulated, while there was virtually no difference...
by szellmann
Mon Dec 12, 2016 8:17 am
Forum: General Development
Topic: Multiple Textures CUDA/OpenCL
Replies: 8
Views: 9741

Re: Multiple Textures CUDA/OpenCL

In my personal experience the __global char* approach is very fast even if it's not hardware accelerated. I'm curious, what difference in latency do you actually observe when comparing nearest neighbor vs. linear filtering. My rt lib has a dedicated CPU API where you can call texture access "i...
by szellmann
Thu Dec 08, 2016 10:37 am
Forum: General Development
Topic: Multiple Textures CUDA/OpenCL
Replies: 8
Views: 9741

Re: Multiple Textures CUDA/OpenCL

From CUDA 6.0 or so onwards, and on Kepler and newer, you can use texture objects. I'd guess that they are quite efficient, just as bindless textures in OpenGL are. You can have a dynamic number of texture objects / can pass a list (e.g. thrust::device_vector) of texture objects to the kernel. For l...

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