Search found 84 matches

by friedlinguini
Sun Feb 10, 2019 2:51 pm
Forum: General Development
Topic: Performance issues with Wald&havran's nlogn kdtree construction
Replies: 5
Views: 211

Re: Performance issues with Wald&havran's nlogn kdtree construction

Calculating a median can be O(n) (see std::nth_element, median-of-median algorithm, etc), so the overall algorithm I described should run in O(n log n).

If you’re using a language that doesn’t have a linear median/partition library function, then that can be a bit of a rabbit hole.
by friedlinguini
Fri Feb 08, 2019 2:01 am
Forum: General Development
Topic: Performance issues with Wald&havran's nlogn kdtree construction
Replies: 5
Views: 211

Re: Performance issues with Wald&havran's nlogn kdtree construction

Seems like unnecessary complexity to use a SAH construction algorithm just to organize a point cloud. Especially if the heuristic is just a median split. That means you don't need to do a plane sweep or a full sort. I'd also get rid of mixing component values from different dimensions. As you've not...
by friedlinguini
Thu Sep 20, 2018 3:19 pm
Forum: Links & Papers
Topic: CUDA 10 available
Replies: 6
Views: 9095

Re: CUDA 10 available

I don't think CUDA itself has been advertised with ray-tracing goodness; it's all delegated to OptiX, DirectX, and Vulkan.
by friedlinguini
Wed Jul 25, 2018 3:24 am
Forum: Links & Papers
Topic: Primary Sample Space Path Guiding
Replies: 3
Views: 1576

Re: Primary Sample Space Path Guiding

It seemed to have a lot of the same ideas as multidimensional adaptive sampling (https://www.ci.i.u-tokyo.ac.jp/~hachisuka/mdas.pdf), and also the same weaknesses.
by friedlinguini
Mon Jul 23, 2018 1:44 pm
Forum: General Development
Topic: Emissive surfaces and visibility term
Replies: 6
Views: 2248

Re: Emissive surfaces and visibility term

I'd say no. Without explicit light source sampling, all geometric factors relating to the light source--surface area, distance, and cosine term--are accounted for in the probability of a ray hitting the light source "by accident." For example, if the geometric normal of a triangular light ...
by friedlinguini
Thu Jun 15, 2017 1:59 pm
Forum: Visuals
Topic: My First Spectral rendering
Replies: 5
Views: 5924

Re: My First Spectral rendering

Whoah, weird. I had thought you could do something very similar, but by adding a random point on the *interior* of a sphere to the normal, rather than on the surface: http://psgraphics.blogspot.com/2014/09/random-diffuse-rays.html. Obviously it would be better to use exactly two random parameters th...
by friedlinguini
Mon Apr 17, 2017 10:30 pm
Forum: Tools, Demos & Sources
Topic: Implementation for Blue-noise Dithered Sampling
Replies: 26
Views: 19106

Re: Implementation for Blue-noise Dithered Sampling

The idea ideas not adding a deterministic (blue-noise) number to a random number. In fact, the idea is to get rid of the randomness altogether - you use the deterministic number to post your pattern, instead of using a random number. Right, I was using "random" loosely. My understanding o...
by friedlinguini
Sun Apr 16, 2017 8:34 pm
Forum: Tools, Demos & Sources
Topic: Implementation for Blue-noise Dithered Sampling
Replies: 26
Views: 19106

Re: Implementation for Blue-noise Dithered Sampling

sin(2 * pi * (ps - qs)) * 0.5 + 0.5


OK, that makes no sense. I tried to jam a couple of ideas together without making sure that one didn't break the other.

Maybe c * (x - x * x), where x = ps - qs and c is some constant I haven't worked out yet.
by friedlinguini
Sun Apr 16, 2017 2:19 pm
Forum: Tools, Demos & Sources
Topic: Implementation for Blue-noise Dithered Sampling
Replies: 26
Views: 19106

Re: Implementation for Blue-noise Dithered Sampling

I was thinking of giving this technique a spin, and I had a couple of random thoughts. 1. The idea is basically to add the pixel-dependent blue-noise shift to a pixel-independent random number, and subtract 1 if necessary to bring things in the range of [0, 1), right? But during tile generation, the...
by friedlinguini
Mon Feb 06, 2017 2:41 pm
Forum: General Development
Topic: Dispersion
Replies: 2
Views: 5196

Re: Dispersion

According to most sources, including https://en.wikipedia.org/wiki/SRGB, the linear RGB values are usually clipped to [0.0, 1.0], with display white represented as (1.0, 1.0, 1.0). It's not entirely clear, but it sounds like you're talking about clamping individual samples. Don't do that. Just aver...

Go to advanced search