Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [pathtracing]

For questions about the path tracing Monte Carlo algorithm for physically accurate global illumination, or its variants.

221 questions
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Path Tracing & Materials

I'm wondering about the technique used when sampling a layered material for the next event in a path tracer. I have a material with three layers: a base diffuse, specular and sheen lobes. How does one go about choosing a discrete layer to sample for…
Mark Davies
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Proper way to handle diffuse + refraction + reflection rays in path tracing?

Let's say we are path tracing and that there is an object which has some amount of diffuse reflection, and some amount of specular reflection. What is the best or correct way to handle that in the path tracer? Looking at smallpt…
Alan Wolfe
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Is it expected that a naive path tracer takes many, many samples to converge?

I have a naive diffuse/emissive material path tracer implementation (pinhole camera) and am seeing it take a very large number of samples per pixel to converge - like probably in the millions - and was wondering if that was normal for "naive" path…
Alan Wolfe
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How does path tracing handle specular surfaces(Dirac BSDFs) such as water?

I'm trying to render water using path tracing. However, since in path tracing, the light sampling is skipped while the intersection point is perfect specular and thus no direct light would be taken into account. So does that mean all…
jinglei
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Path Tracer - implementation questions

so I am currently in the middle of implementing a path tracer for my bachelor thesis. And so far I have understood and mapped the general flow of the program except for 2 things. Note that I'm using OpenCL and will be using OpenGL-OpenCL interop for…
gallickgunner
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Can I ignore importance, adjoint equations, GRDFs for my path tracer?

I need to write a photo-realistic renderer. I have been looking at ScratchAPixel site, asking a couple of questions here on CG, and going through the Advanced Global Illumination 2nd ed book. I've read about radiometry, probability, Monte Carlo, and…
PeteUK
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How to implement explicit light sampling when implementing path tracing?

I implemented a path tracer and got a similar result like this one. Sample: 4096, time used: 537.05s The algorithm is exactly the same as the one in wikipedia, where only the Gathering Path is considered. In this answer, @Nathan Reed said that…
zwcloud
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Why is Russian Roulette used in ray tracing?

Why should we use Russian Roulette? Does it reduce ray tracing artifacts?
bitWise
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Strange artifacts while rendering a dielectric material

I am trying to render a dielectric sphere inside the Cornell Box. Some circles are generated on the sphere. Here is the photo generated by path tracer: And below is my main function: function trace(surfaces::Array{Surfaces, 1}, ray::Ray,…
bitWise
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Should I expect differences with explicit light sampling other that the noise?

I am trying to understand why my explicit light sampling implemetation does not produce the same results as my naive path tracer. Here are my results : Naive Version : Explicit light sampling version : Diff : It's not that different, but the top…
Aulaulz
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What does 'free-path' mean?

I've seen some phrases like 'free-path', 'free-path distributions', 'mean free path' in some computer graphics resources, but none of them explains what does these phrases mean, does anyone have an explanation of these phrases? Thanks a lot!
Wenjian Zhou
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Path tracing: How to do tone mapping and gamma correction?

I am not sure what is the correct way to do tone mapping and gamma correction in a Monte-Carlo Path Tracer. Should I apply tone mapping before or after averaging the samples?
dblouis
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Path tracing best materials to learn

i want some of your advices. To begin with i ve never studied computer graphics and i want to do a project with Path tracing which i didnt find the right materials to begin with. Is it recomeneded to start directly learn Path tracing or i have to…
Mr.me
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smallpt's early clamping

Kevin Beason's smallpt estimates the pixel radiance by accumulating $2\times2$ subpixel radiance estimates using the following expression: c[i] = c[i] + Vec(clamp(r.x),clamp(r.y),clamp(r.z))*.25; Here, c[i] represents the radiance estimate of the…
Matthias
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PBRT path tracing: negation of ray direction before next event estimation

I am very new to computer graphics, so I am sorry if this results in a stupid question. For educational purposes I am looking through the pbrt code and I have noticed that before computing the direction for the next path for the subsequent bounce,…
jackten
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