Questions tagged [pbr]
The pbr tag has no usage guidance.
78
questions
1
vote
1
answer
1k
views
Roughness Value of (Close to) Zero in Physically Based Rendering
In my Direct Light Physically Based Renderer, when I set the roughness too low (ie. 0.0 or close) the specular reflection doesn't show, not even at high resolutions and at perfect angle with the ...
1
vote
1
answer
961
views
Understanding the irradiance map generation
I am trying to understand how the generation of irradiance maps works. I was reading LearnOpengGL tutorial and Codinglabs article. Reading those articles, I got a bit confused about how we use ...
5
votes
3
answers
784
views
What is the purpose of the projected solid angle $dA^\perp$ term in the definition of Radiance?
In the definition of Radiance, which according to PBRT is defined as
flux per unit solid angle $d\omega$ per unit projected area $dA^\perp$
$$L_i=\frac{d\Phi}{d\omega\ dA^\perp}$$
My original ...
3
votes
1
answer
385
views
Strange dark spot when lighting in deferred rendering PBR shaders
It's probably something obvious but there seems to be a strange issue with lighting in my pipeline. I'm trying to keep everything in world space at the moment for simplicity but cannot figure out what'...
2
votes
1
answer
132
views
how many watts are in the SPD of the color white?
Please help. I'm trying to implement a ray tracer, going by the PBRT book and got stuck on an issue that I fail to find the answer to. My scenes are made from objects and light sources. From that, I ...
2
votes
1
answer
367
views
Why is cos(𝜃) in the denominator in the reflectance equation and in the numerator in the shading equation?
Background: I'm reading https://learnopengl.com/PBR to learn about PBR. In the theory slide (https://learnopengl.com/PBR/Theory), the author has the reflectant equation as
The theta (the angle ...
1
vote
1
answer
227
views
How to implement physically based unit in pbr renderer
According to this note, Frostbite use photometry unit in their calculation. I am trying to mimic this feature, but I am not sure what transformation need to be done. I will try to explain what I have ...
1
vote
0
answers
84
views
Questions about BRDF parameterization
Hi I'm trying to get a better understanding of the BRDF modeling. I only implemented naive diffuse(lambert), specular and microfacet BRDF before, but I don't have much experience in mixed BRDFs and ...
1
vote
0
answers
880
views
GGX BRDF is greater than 1?
I am implementing a GGX BRDF, this is the formula I used is from:https://schuttejoe.github.io/post/ggximportancesamplingpart1/
And this is my implementation:
...
0
votes
1
answer
587
views
How Image Based Lighting is applied to indoor scene?
Now the mainstream engine's approach is to use image-based lighting to achieve approximate global illumination, but such a technique seems to be only applicable to outdoor scenes.What kind of ...
2
votes
1
answer
184
views
Why can I see the diffuse lighting effect on a perfect mirror?
Currently I am learning PBR by Unity3D. I find that even I turn the smoothness to 1, I can still see the diffuse lighting effect, which does not make any sense to me.
Imagine I trace a ray from my ...
0
votes
1
answer
343
views
Weirdly looking diffuse irradiance map
I have problem with creating diffuse irradiance map. As reference I am using https://learnopengl.com/PBR/IBL/Diffuse-irradiance and https://github.com/TheEvilBanana/PhysicallyBasedRendering/blob/...
3
votes
1
answer
807
views
Iridescence/Thin-film interference integration as a layer
I'm trying to integrate the thin-film interference effect described in the paper "Belcour, L., & Barla, P. (2017). A practical extension to microfacet theory for the modeling of varying ...
1
vote
0
answers
91
views
confused on isotropic BRDF
I am reading a paper and there is a part I don't understand:
I am wondering why the isotropic BRDF only depends on the view direction and roughness? Why is the light direction not related?
2
votes
1
answer
264
views
Confused on reflection coeffcient of Fresnel equations
I am reading a paper about layered materials. However, I am confused on the implementation of this paper. The following picture describe the layered material.
r_ab is a complex reflection coeffcient ...