Questions tagged [pathtracing]
For questions about the path tracing Monte Carlo algorithm for physically accurate global illumination, or its variants.
246 questions
2 votes
1 answer
83 views
How do you derive the integral equation of transfer in the PBRT book?
In the PBRT book section on the equation of transfer, they give the equation $\frac{\partial}{\partial t}L_o(p',\omega) = -\sigma_t(p',\omega)L_i(p',-\omega)+\sigma_t(p',\omega)L_s(p',\omega)$, and ...
- 87
1 vote
0 answers
103 views
How does PBRT rewrite the majorant transmittance integral over segments when sampling the majorant transmittance?
In the PBRT book section on Sampling the Majorant Transmittance, they take the equation: $\int_0^t \sigma_{maj}(p')T_{maj}(p \to p')f(p')dt'$, and using the multiplicative property of transmittance $...
- 87
1 vote
1 answer
85 views
How is this null-scattering transmittance equation in PBRT derived?
In the PBRT book section on null scattering, they define the null-scattering coefficient $\sigma_n$ and the constant majorant $\sigma_{maj}$, and define the equation: $\frac{dL_o(p, \omega)}{dt} = -(\...
- 87
0 votes
0 answers
55 views
Handling probabilities with Spectral "Null Tracking"
I have confused myself to the point where i dont know what up or down are. I will try to keep things focused, but certain decisions may need a paragraph of motivation. For some time now me and a ...
- 121
0 votes
0 answers
43 views
Convergence of Microfacet BRDF vs Primitive BRDFs
I have been implementing a path tracer - while I initially started the process using a dummy Lambertian diffuse BRDF to focus on the base path tracer, I recently added a microfacet BRDF as an option. ...
1 vote
1 answer
180 views
Monte Carlo integration of the Path Space integral
In Eric Veach's thesis, chapter 8.2.2, he says that: Our goal is to estimate the path integral: $$I_j = \int_{\Omega}f_j(\overline x) d\mu(\overline x)$$ for each measurement $I_j$. To do this, the ...
- 11
3 votes
1 answer
248 views
Wavelength to RGB conversion issue. Average RGB result is yellow tinted instead of white
I'm currently implementing dispersion in my RGB path tracer. How I do things: When I hit a glass object, sample a wavelength uniformly between 360nm and 830nm and assign that wavelength to the ray ...
- 301
3 votes
1 answer
158 views
One-sample multiple importance sampling, with environment and brdf
I am writing a pathtracer, and I want to somehow incorporate importance sampling of the environment map. The obvious way to do this seems to use MIS to either importance sample from my material bsdf ...
