Questions tagged [pbr]
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78
questions
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"Charlie" Sheen BRDF's directional albedo integrates to values higher than 1 at low roughnesses. Does this mean it is not energy conserving?
I am implementing the BRDF from the 2017 paper "Production Friendly Microfacet Sheen BRDF". This BRDF is modelled as a coat layer stacked on top of a base specular. In order to do so in an ...
- 53
1
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1
answer
236
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Confusion over Microfacet-based BRDFs and Normal Distribution Functions
Through reading various sources online, I've become a bit confused. I'll briefly outline what I think I do understand:
My understanding is that microfacet-based BRDFs assume there is always a perfect ...
- 229
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63
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Unable to compute fresnel reflections properly
I am implementing fresnel reflections for materials in my renderer.
According to this source, here the look I should obtain when rendering a sphere over a grey background:
I have two implementations. ...
- 103
0
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1
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164
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Does fresnel reflection make sense for metals?
I am implementing fresnel reflections for materials in my renderer.
Does it make sense for metals?
Here my implementation:
...
- 103
0
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0
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169
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One-sample model Multiple Importance Sampling with balance heuristic
Recently I feel a bit confused about one-sample model MIS. One sample model MIS can be found here in Veach 1997. 9.2.4 The one-sample model, and this one-sample model is widely used in the opensource ...
- 1,077
1
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1
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93
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Shading normal and geometric normal for refractive surface rendering
I got confused when implementing my own renderer. I read this from the PBR-book:
Fortunately, there is an elegant solution to these problems. When evaluating the BSDF, we can use the geometric normal ...
- 1,077
1
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0
answers
68
views
replace IBL with single color - the lighting equation
I want to avoid IBL (image based lighting), however my scenes are way too dark - especially close-to-mirror like surfaces, which get little contributions from other direct light sources in the scene.
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1
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1
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174
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The purpose of NdotV in the directional-hemispherical reflectance equation in the book "Real-time rendering book"
I have been reading the book "real-time rendering 4th edition" and came across this Directional-hemispherical reflectance equation.
$$R(\mathbf{l}) = \int_{\mathbf{v}\in\Omega} f(\mathbf{l}, ...
1
vote
1
answer
66
views
Is the dichromatic model physically based?
lately I have been learning about photometry, and everywhere I look I see a BRDF written according to the "dichromatic model". Roughly speaking: $$\rho= \rho_D+\rho_S \cdot (...)$$
for some $...
- 113
1
vote
0
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94
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Why my bsdf can not pass Chi2test?
I implemented a MicrofacetTransmission in nori. But it can not pass all Chi2test when alpha is large(>= 0.4 or ?),part of chi2test is passed.And I can not found the problem.Can someone help me?
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- 31
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126
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how can I compute a roughness map without any 3D softwares?
Recently, I want to use a roughness map to get better rendering results.
Most information on the internet is about the operation of 3D software.
So, how can I generate a roughness map of my own 3D ...
1
vote
1
answer
151
views
Conflicting definitions for the distribution of normals $D$ in microfacet BSDFs
Please do not confuse this question with this one. In Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs, Eric Heitz defines the distribution of normals as.
There, the footnote. ...
1
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0
answers
132
views
Contour-line looking artifact on diffuse irradiance map
I tried implementing my own diffuse irradiance map maker after reading Learn OpenGL > PBR > IBL > Diffuse Irradiance.
It takes an HDR image and makes six HDR cube map.
But It keeps making ...
- 111
0
votes
1
answer
96
views
PBR pipeline with multiple HDR images?
I believe I already know the answer to this question, but I want to make sure I'm understanding this correctly. Within a physically based rendering pipeline, you calculate your indirect lighting from ...
- 105
3
votes
1
answer
208
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Confusion of deriving the Jacobian of the reflection transformation in Walter et. al's 2007 paper
When deriving the Jacobian of the reflection transformation in Walter et. al's 2007 paper:
First we have a macrosurface BSDF which is:
$f_{s}(\mathbf{i}, \mathbf{o}, \mathbf{n})=\int\left|\frac{\...
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