Questions tagged [brdf]
149 questions
24
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3 answers
What is the difference between radiance and irradiance in BRDF
Currently I am reading the BRDF section from Real Time Rendering and I am having a hard time to visually understand the definition of this function. BRDF is the ratio between the radiance in outgoing direction and irradiance of incoming direction. I…
kevinyu
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14
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1 answer
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 ratio of radiances?
PeteUK
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9
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Diffuse BRDF component of the Disney BRDF
In the SIGGRAPH course:
BURLEY B.: Physically Based Shading at Disney, SIGGRAPH 2012 Course: Practical Physically Based Shading in Film and Game Production, 2012.
it is mentioned that some BRDF models include a diffuse Fresnel factor such…
Matthias
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6
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2 answers
What does "Bidirectional" in BRDF mean?
So Bidirectional essentially means "two directions", right? But what are these two direction (left-right? up-down? north-south?) we are talking about in regards to bidirectional reflectance distribution function (BRDF), bidirectional scattering…
Kristoffer Helander
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2
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2 answers
What is slope distribution
I was reading this slope space integral paper. Can anyone help to explain slope space and slope distribution mentioned in this paper, and why we can use normal and half vector to represent 2D positions in slope space? Thanks!
SSS
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2
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2 answers
Why is the symbol for solid angle a small omega in the definition of the BRDF?
In many resources the BRDF is defined like $$f_{r}(\omega_{i},\omega_{r}) = \frac{\mathrm{d}L_{r}(\omega_{r})}{L_{i}(\omega_{i})\,\cos{\theta_{i}}\,\mathrm{d}\omega_{i}}.$$ The index $r$ might be replaced by $o$ but overall the equation looks…
akuzminykh
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1
vote
1 answer
Value range of normal distribution function
Is the normal distribution term D in the Cook-Torrance BRDF supposed to be between 0 and 1? What does this number actually represent?
dblouis
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1
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1 answer
Ask for detailed derivation of a formula in "Advanced Global Illumination"
Attached is page 34 of "Advanced Global Illumination", 2nd edition, by Dutre et al. I don't understand how (2.22) is derived from (2.21) and the given incident radiance distribution $L(x\leftarrow\Psi)=L_{in}\delta(\Psi-\Theta)$. Could you please…
user5280911
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How to understand Beckmann is a Gaussian distribution in slope space
I'm recently looking into how slope space is used in microfacet BRDF. Can anyone help to explain how Beckmann is a Gaussian distribution in slope space? Thanks
SSS
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0
votes
1 answer
What is the terminology for the brightest point on a plane
Given a plane, assuming that view direction and light direction are both fixed, there must be point which is the brightest point on that plane(where half vector equals to the normal vector).What is the terminology for that point?(Assuming we are…
Chris Guo
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