Search found 29 matches

by Geometrian
Wed Jun 18, 2014 1:08 am
Forum: General Development
Topic: Energy-Conserving Phong Specular Lobe
Replies: 10
Views: 8538

Energy-Conserving Phong Specular Lobe

I am trying to get correct Phong specular for a simple path tracer. The test scene is a plane with no diffuse but a specular component. Above the plane is a dome emitting light <0.5,0.5,0.5>, with no reflection at all. The camera is inside the dome. The dome appears gray and, since every ray bouncin...
by Geometrian
Thu Aug 22, 2013 10:55 pm
Forum: General Development
Topic: Dielectric BRDFs
Replies: 6
Views: 5309

Re: Dielectric BRDFs

How exactly is it "not working"? It just doesn't look right. The specular coefficient is very small for almost everything except glancing angles. To be fair, I haven't tried rendering real scenes with it--just the BRDF's specular looks too small. First of all, are you using the common form of the F...
by Geometrian
Thu Aug 22, 2013 7:52 pm
Forum: General Development
Topic: Dielectric BRDFs
Replies: 6
Views: 5309

Dielectric BRDFs

Hi, I'm trying to get a general BRDF for dielectrics. As I see it, there are three major ways light scatters: diffuse reflection, specular reflection, and transmission (the first two modeled with Phong). What I'm having trouble figuring out is how to weight the probability of each. I can create a BR...
by Geometrian
Tue Aug 06, 2013 9:40 pm
Forum: General Development
Topic: Computing Explicit Light Sampling Weights
Replies: 3
Views: 4392

Re: Computing Explicit Light Sampling Weights

For people of the future, I figured it out.
by Geometrian
Wed Jul 31, 2013 11:34 am
Forum: General Development
Topic: My Reformulation of the Rendering Equation (+Applications)
Replies: 7
Views: 6169

Re: My Reformulation of the Rendering Equation (+Application

you removed (N*w) from brdf and made it non symmetric So that's why it's in there! I pulled the N*w_o term out since its function is the same as the N*w_i term, just the other way. I maintain that this way is clearer. Em not measure radiance any more Actually, I see that as a benefit. The extra emi...
by Geometrian
Tue Jul 30, 2013 10:56 pm
Forum: General Development
Topic: My Reformulation of the Rendering Equation (+Applications)
Replies: 7
Views: 6169

Re: My Reformulation of the Rendering Equation (+Application

Keep in mind I don't know it's right. I've have used it to rederive SmallPT's diffuse term (and I just now used it to rederive the weighting for explicit light sampling; I'll add that in soon), but that doesn't mean it's necessarily correct.
Thanks for reading! :)
by Geometrian
Tue Jul 30, 2013 4:48 am
Forum: General Development
Topic: My Reformulation of the Rendering Equation (+Applications)
Replies: 7
Views: 6169

My Reformulation of the Rendering Equation (+Applications)

Hi, After a lot of work, reverse engineering, and guessing, I came up with a somewhat different formulation of the rendering equation which I find far more clear and intuitive (if more verbose) than everything else I have seen. It looks like this: http://latex.codecogs.com/gif.latex?%5Cvec%7BL%7D%28...
by Geometrian
Mon Jul 29, 2013 2:31 pm
Forum: General Development
Topic: Computing Explicit Light Sampling Weights
Replies: 3
Views: 4392

Re: Computing Explicit Light Sampling Weights

Actually, I took another crack at the explicit light sampling in the modification of SmallPT (also found this , too late). Ultimately, the formula they're using is very close to the one I'd expect--it's just off by a factor of 1/2, and I don't know why. I thought about it some more, and I expected t...
by Geometrian
Mon Jul 29, 2013 12:02 am
Forum: General Development
Topic: Computing Explicit Light Sampling Weights
Replies: 3
Views: 4392

Computing Explicit Light Sampling Weights

Hi, I have implemented an OpenCL-accelerated path tracer, and am trying to add explicit light sampling. I turned up SmallVCM and tried to reverse engineer their algorithm. I also found this thread , which leads in another direction. My test scene is a Cornell box with two spheres and a single, small...