## Search found 79 matches

Thu Jun 15, 2017 1:59 pm
Forum: Visuals
Topic: My First Spectral rendering
Replies: 5
Views: 3423

### 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...
Mon Apr 17, 2017 10:30 pm
Forum: Tools, Demos & Sources
Topic: Implementation for Blue-noise Dithered Sampling
Replies: 26
Views: 11903

### 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...
Sun Apr 16, 2017 8:34 pm
Forum: Tools, Demos & Sources
Topic: Implementation for Blue-noise Dithered Sampling
Replies: 26
Views: 11903

### 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.
Sun Apr 16, 2017 2:19 pm
Forum: Tools, Demos & Sources
Topic: Implementation for Blue-noise Dithered Sampling
Replies: 26
Views: 11903

### 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...
Mon Feb 06, 2017 2:41 pm
Forum: General Development
Topic: Dispersion
Replies: 2
Views: 2714

### 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...
Mon Dec 12, 2016 2:58 pm
Forum: General Development
Topic: Multiple Textures CUDA/OpenCL
Replies: 8
Views: 10825

### Re: Multiple Textures CUDA/OpenCL

I remember sth. along the lines of the CPU linear filter being 5x slower than nearest filtering. In contrast to that, On the GPU, with HW accelerated filtering, I found there was virtually no difference in performance between nearest and linear filtering. How did you lay out your textures in memory...
Tue Dec 06, 2016 1:32 pm
Forum: General Development
Topic: Confused about near-specular reflection that is not energy conserving.
Replies: 4
Views: 3000

### Re: Confused about near-specular reflection that is not energy conserving.

There's no reason to give up on point lights; all I was trying to say is that having a BRDF that spikes above 1 is physically plausible. If a point light is bright enough to visibly illuminate a diffuse surface, then it's going to create a very bright highlight on a near-mirror surface. The intensit...
Fri Dec 02, 2016 4:17 pm
Forum: General Development
Topic: Confused about near-specular reflection that is not energy conserving.
Replies: 4
Views: 3000

### Re: Confused about near-specular reflection that is not energy conserving.

BRDFs can have spikes arbitrarily greater than 1 because you use them by integrating over some finite domain, and the integral should give you something less than one (a surface can't reflect more photons than it receives). Consider also a point light above the ground with an intenty Li. The reflect...
Mon Oct 24, 2016 10:45 pm
Topic: Robust Light Transport Simulation via Metropolised Bidirectional Estimators
Replies: 5
Views: 7902

### Re: Robust Light Transport Simulation via Metropolised Bidirectional Estimators

The proposed algorithm shoots and stores one eye path per pixel, and then samples the light path using metropolis sampling, so one light vertex has negligible storage. My best guess is that the NEE isn't strictly necessary, but it speeds things up and helps with stratification. But a guess is all it...
Mon Oct 24, 2016 7:59 pm
Topic: Robust Light Transport Simulation via Metropolised Bidirectional Estimators
Replies: 5
Views: 7902

### Robust Light Transport Simulation via Metropolised Bidirectional Estimators

So I'm going through this paper, which was recently linked from Toshiya Hachisuka's page (http://www.ci.i.u-tokyo.ac.jp/~hachisuka/ups-vcm_mcmc.pdf). The basic idea is trying to marry metropolis light transport with UPS/VCM, which is great. There's one sentence in this paper that's driving me a bit ...