Questions tagged [pbr]
The pbr tag has no usage guidance.
7
questions
2
votes
0
answers
164
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Scaling of the final image in Metropolis Light Transport
I don't understand why the PBR implementation of Metorpolis Light Transport scales the final image by b / mutationsPerPixel.
The authors write:
Each Metropolis ...
- 203
23
votes
2
answers
8k
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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 ...
- 4,420
12
votes
1
answer
814
views
Rendering in radiometric units or photometric?
In traditional rendering, it is typical to do all the calculations with radiometric units, either as full spectral rendering, or component-wise (XYZ, RGB, etc).
However, as modern rendering adds more ...
- 3,792
12
votes
2
answers
3k
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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 $1/(2\pi)$?
- 520
6
votes
1
answer
819
views
The reciprocity of BRDF
Many books describe that a BRDF has the following property (reciprocity):
$$f_r(x, \Theta \to \Psi ) = f_r(x, \Psi \to \Theta)$$
Why is the above equation correct?
I think the above equation ...
- 523
1
vote
1
answer
2k
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Can't understand the Importance sampling GGX
I've read many articles relating to importance sampling of GGX. However, I still feel confused.
The formula of GGX is :
And many article says we should use this formula to sample:
In the formula, ...
- 187
0
votes
2
answers
495
views
PBR : Understanding importance sampling
I have read this article
On PBR and in it we have NDF function defined as follows
Then I have read this article on random vector generation
Here are what I feel are the important bits.
Now jump to ...
- 179