All Questions
Tagged with pbr raytracing
12
questions
1
vote
0
answers
94
views
Why my bsdf can not pass Chi2test?
I implemented a MicrofacetTransmission in nori. But it can not pass all Chi2test when alpha is large(>= 0.4 or ?),part of chi2test is passed.And I can not found the problem.Can someone help me?
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- 31
0
votes
2
answers
499
views
Ray Tracing, why does the GGX make my rendering result darker and darker for each frame?
I am trying to add GGX and PBR textures to my GPU ray tracer. The result is very strange, it's getting darker for each frame.
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- 131
1
vote
0
answers
70
views
How to handle negative reflection directions in raytracing?
I got a function that generates samples from a GGX visible normal distribution function. When I use it to calculate reflection directions obviously some of these intersect with the surface agin (...
- 11
0
votes
0
answers
86
views
Considering a path generated by bidirectional path tracing under a different strategy
Say I have constructed a path, using bidirectional path tracing (BDPT), consisting of a light subpath $y$ with $s=2$ vertices and a camera subpath $z$ with $t=3$ camera vertices.
Now I want to ...
- 203
2
votes
0
answers
164
views
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 ...
- 203
0
votes
0
answers
66
views
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 ...
- 203
0
votes
0
answers
53
views
Distribution of the first vertex on a camera subpath in bidirectional path tracing
Suppose we are sampling camera rays of a perspective camera with a finite aperture. The PBRT implementation of the sampling scheme looks like this:
...
- 203
0
votes
0
answers
212
views
Multiple Importance Sampling in Bidirectional Path Tracing
I'm trying to understand the computation of the path density described in the book Physically Based Rendering. They assume that a path $$x=(x_0,\ldots,x_{n-1})=(q_0,\ldots,q_{s-1},p_{t-1},\ldots,p_0)$$...
- 203
5
votes
3
answers
784
views
What is the purpose of the projected solid angle $dA^\perp$ term in the definition of Radiance?
In the definition of Radiance, which according to PBRT is defined as
flux per unit solid angle $d\omega$ per unit projected area $dA^\perp$
$$L_i=\frac{d\Phi}{d\omega\ dA^\perp}$$
My original ...
- 222
2
votes
1
answer
132
views
how many watts are in the SPD of the color white?
Please help. I'm trying to implement a ray tracer, going by the PBRT book and got stuck on an issue that I fail to find the answer to. My scenes are made from objects and light sources. From that, I ...
- 23
3
votes
0
answers
521
views
Mathematics of Sub Surface Scattering
Can somebody help explain the mathematics of Sub Surface Scattering in a Path Tracer based on the Diffuse Approximation in A Practical Model for Subsurface Light Transport ?
I would like someone to ...
- 2,511
4
votes
1
answer
105
views
How is measured BRDF data recorded?
How is measured BRDF data recorded? Like the MERL BRDF Database.
What kind of equipment is used and what are the key values that need to be recorded?
I know one place this data was used was in the ...
- 2,511