Questions tagged [brdf]
The brdf tag has no usage guidance.
24
votes
2answers
3k views
Path tracing the Cook-Torrance BRDF
-- Sorry for the long post, but I prefer to do that way because "Devil is in the details." :)
I am writing a path tracer from the scratch and it is working nicely for perfectly diffuse (Lambertian) ...
34
votes
2answers
4k views
How physically-based is the diffuse and specular distinction?
The classical way of shading surfaces in real-time computer graphics is a combination of a (Lambertian) diffuse term and a specular term, most likely Phong or Blinn-Phong.
Now with the trend going ...
13
votes
1answer
2k views
Choosing Reflection or Refraction in Path Tracing
I am trying to implement refraction and transmission in my path tracer and I'm a bit unsure on how to implement it. First, some background:
When light hits a surface, a portion of it will reflect, ...
1
vote
0answers
158 views
Normal Artifacts On Grazing Angles
I am currently experiencing a very obvious artifact that occurs when looking at objects on very grazing angles
Here is a picture of the artifact:
I noticed that the issue was coming from my ...
17
votes
2answers
4k views
How to properly combine the diffuse and specular terms?
As far as I understand, in a BRDF the Fresnel term is telling us the probability for a photon to be reflected or refracted when it hits a surface.
The reflected photons will contribute to the ...
10
votes
1answer
275 views
Why isn't a BRDF a ratio of radiances?
I'm Learning about BRDFs and wondering why the BRDF is defined as the ratio of outgoing radiance to a given direction and incoming irradiance from another direction. Why isn't the BRDF defined as ...
5
votes
1answer
461 views
Energy conservation of BRDF
I'm reading Advanced Global Illumination.
Here is the part confusing me:
What do the second equation and $\delta$-function mean?
Why the third equation is a sufficient condition even though a reason ...
6
votes
2answers
2k views
Refraction in a Ray Tracer: What do with an intersection within the medium?
I am currently following a tutorial at Scratchapixel.com on refraction
Here is the refract function:
...
6
votes
1answer
409 views
Fresnel and specular colour
I'm trying to implement Cook-Torrance BRDF and had previously bookmarked this question as it looked very well thought out. Going through it, I'm confused about the Fresnel equation. The author has the ...
5
votes
1answer
729 views
Volume Rendering (Path Tracing & Real-Time)
I have a few doubts and questions regarding volume rendering, I was hoping someone here could help me understand.
I commonly hear the terms 'Ray-Marching' & 'Volume Rendering' being used together ...
8
votes
1answer
648 views
Why normalise Lambertian BRDF by 1/pi?
Why is a Lambertian BRDF normalised by dividing by $\pi$? Since the area of a unit sphere is $4 \pi$, and the area of the half sphere above the surface is $2 \pi$, shouldn't it rather be $1/(2\pi)$?
