# Questions tagged [physically-based]

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22 questions with no upvoted or accepted answers
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### How correct is rendering in XYZ / linear RGB space?

I have a spectral power distribution (SPD, 5 nm steps) for all light sources in the scene and SPDs for the reflectance of all surfaces under any light / viewer angle in question. I'm going to ...
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### Would the surface of a large carbon-nanotupe structure look metalic?

CNT is a promising new material, which Wikipedia describes as such: Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual ...
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### Is there a material table for the Cook Torrance BRDF?

Is there a material table that lists all the specific values to obtain a certain type of material (e.g: copper or asphalt) available? I found this table in the paper: A Reflectance Model for ...
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1 vote
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### Term confusion about volume scattering

We have two different terms, for example, let's talk about scattering only. Scattering coefficient Scattering cross-section These two terms are supposed to have different physical meaning. I read it ...
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### Difficulty in understanding the interpretation of propagation of an exitant function from the book Advanced Global Illumination (2nd ed)

The book defines operator $\mathcal{T}$ for the propagation of an exitant function as: if I'm assuming that the position of the point $x$ is on the top-left surface, and that $\Psi$ is considered as ...
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1 vote
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### Image contribution function and reconstruction using filters

So I've been reading Physicall Based Rendering which in section 16.4.3 defines the "image contribution function" to be the following $$I_j = \int_\Omega h_j(X)L(X)d\Omega$$ where the variables are ...
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1 vote
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### Compute emitted importance of a pinhole camera

In section 16.1.1 of Physically Based Rendering the authors describe how we can check, if a given ray $r$ corresponds to one starting from the film area. They implement this check such that it works ...
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1 vote
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### Interpreting Cornell Box data for path tracer

So I want to path trace a Cornel Box scene, but I don't understand the values given here in section 2 and 3. Cornell Box Data | Cornell University Program of Computer Graphics No.2 Lists surface ...
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1 vote
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### How to validate whether a reflection model is implemented correctly?

I think this is one of the most important part when you write a physically-based renderer. The solution I came up with is to put a sphere to the scene with a constant background radiance. Solve the ...
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1 vote
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### Mitsuba Bidirectional Framework

I'm confused by the Mitsuba bidirectional framework for quite a while now, especially by the different eval and connect ...
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