# Questions tagged [pbrt]

For questions related to techniques described in the book *Physically Based Rendering: From Theory to Implementation*

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### PBRT - Transforming between Distributions (Section 2.4)

In the 4th edition of "Physically Based Rendering" here: pbrt book 4th ed Section 2.4 in Section 2.4 "Transforming between Distributions", it is said "Suppose we are given a ...
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### How are these two projection matrices related?

I have two 3D perspective projection matrices $A,B$ with standard projection parameters $k=\cot(\theta/2)$, where $\theta$ is the field of view, $n$ is the $z$-near value, $f$ is the $z$-far value, ...
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### Distance sampling with unbiased transmittance estimators

I'm currently trying some things with transmittance estimators in PBRT and I have implemented the following paper: Unbiased Ray-Marching Transmittance Estimator. This method assumes that two points $x$...
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I was reading Deriving radiance from irradiance and intensity and the last comment said that by dividing $r^2$ we convert radiant intensity to irradiance. What confuses me then is the fact that for ...
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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 ...
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### Is casting a shadow ray non-symmetric in pbrt?

According to the description in the book, Scene::IntersectP() "checks for the existence of intersections along the [passed] ray". This operatorion should be ...
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### How to decide which child of BVH to visit based on sign of ray's direction vector?

I'm reading about BVH from PBRT. According to the book, in the linear bvh part using morton encoding: An efficient way to perform a front-to-back traversal without incurring the expense of ...
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