Questions tagged [global-illumination]

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3
votes
1answer
723 views

Efficiently sampling specific surfaces using MIS in path tracing

Apologies for posting two questions in one post, but as they are relevant I kept them in one. Question 1 In the definition of multi sample estimator that Veach has defined, the integrand is the same ...
6
votes
1answer
474 views

How Sunlight is added in Bidirectional Path tracing?

How is distant directional light source(like sun) added in BDPT? If this is an indoor scene that gets sunlight through windows, how is this handled in BDPT(other than to consider Sun as a big disc far ...
2
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0answers
156 views

Picking multiple light sources from a mixture densities

According to Peter Shirely paper, one pdf(probability density function) can be defined for the union of the light sources and pick only one using a random number from this density: $$p(x) = \alpha_1 ...
3
votes
2answers
882 views

Generation of stratified cosine weighted samples on hemisphere

I have had luck with cosine weighted hemisphere samples, and I know how to generate stratified uniform samples, but I wanted to experiment with combining the two. However, how do I correctly stratify ...
3
votes
1answer
102 views

Multiplication of SH coefficient sets representing occlusion and color

Currently I got interested in implementation of Precomputed Radiance Transfer. I decided that occlusion representation (which is not trivial to compute) would be precomputed as CPU raytracing and ...
8
votes
2answers
831 views

Selection of GI techniques working in real time

I'm considering topic of my thesis connected with computer graphics - I would compare some GI techniques which work completely in real time (no precomputation to lightmaps etc. and each frame ...
4
votes
1answer
73 views

Is there a material that contributes to GI, but isn't directly visible?

I am doing renders of the inside of a room. I would like to show a "bird's eye" view of the room, from above the ceiling (outside the room), but still see the interior of the room. An easy way of ...
6
votes
1answer
2k views

What is Radiosity?

After reading a wikipedia article about Global Illumination It mentions a variety of techniques like Ray Tracing, Path Tracing and Ambient Occlusion. One technique it mentions is Radiosity which I don'...
4
votes
0answers
109 views

Should I use nonsymmetric BSDF for refraction in BPT?

I'm implementing bidirectional path tracing. I want to simulate perfect refraction. I read in the Veach thesis that a perfect refraction BSDF is non-symmetric. Does it mean that I need to use ...
3
votes
1answer
230 views

Real time image based lighting for arbitrary BRDFs coordinate alignment

I was trying to understand how real-time illumination happens with image-based lighting. I understood that importance of representing the Environment Map and BRDF in spherical harmonics. Because ...
9
votes
2answers
2k views

Rendering equation - why unsolvable directly?

Why is the rendering equation, introduced by Kajiya in 1986, not solvable directly/analytically?
6
votes
2answers
110 views

Global illumination leading to image variation

I have a 3D scene I use to generate some images which I then process in Matlab. I noticed that when global illumination (GI) is not enabled, rendering always generates exactly the same pixel-for-pixel ...
4
votes
1answer
762 views

How to compensate low amount of rays reaching the light in a Path Tracer

I am trying to implement for research purposes a path tracer, but so far but results are not so good and I will explain you why. The general idea before getting to the code: I am working on paths ...
4
votes
2answers
620 views

Path tracer not rendering shadows

I am trying to implement for research purposes a gradient-domain path tracer. In order to achieve this step I first need a working Path tracer. I have been creating one so far but results are wrong ...
1
vote
1answer
911 views

Spectral path tracing - image color/brightness incorrect

I implemented a spectral path tracing using physically base BRDF models such as Oren-Nayar,Specular Reflection and Transmission, Lambertian. All calculation in the path tracer uses standard illuminant ...
4
votes
1answer
648 views

Modern Screen Space Ambient Occlusion Techniques

Down the road, I'm planning to implement one or another GPU based ambient occlusion technique. My goal will be to approximate a physically based offline renderer, so I was pretty happy when Wikipedia ...

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