Development Journal of a Raytracer

I think I finally found and fixed all the bugs with the implementation of the Ward BRDF shader. The first one of today was simple, the paper had a small error, an arctan was missing from an equation. I found out because of another paper, Notes on the Ward BRDF by Bruce Walter. I tried it, but the result was mostly the same. I went through the calculations again and then finally saw, that I had forgotten a sin(theta) when I calculated the new half-vector. Fixing that resulted in a proper image (see the linked big image).

Now it is much closer to what I would expect, the circles are all gone and the specular reflections of the light sources have an area of glossy reflections around them. I am only missing reflections of not so brightly lit areas, but perhaps I need a different model for that. I also should rerender the images I have used before.

But I think, I am now really finished with the implementation of the Ward BRDF shader. I will wait until I have done some more tests before I declare it finished, though.