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What they are saying here is wrong or rather extremely simplified for a younger audience.
For optimised ray tracing you don't beam the light from the camera as that has the same chance to bounce to the sun through indirect illumination as a ray from the sun has if it is going to bounce to the camera. What they are saying here is wrong or rather extremely simplified for a younger audience.
For optimised ray tracing you don't beam the light from the camera as that has the same chance to bounce to the sun through indirect illumination as a ray from the sun has if it is going to bounce to the camera. What they are saying here is wrong or rather extremely simplified for a younger audience.
I was wondering that. I don't have anything to do with 3D graphics, but that had occurred to me. What method do they use to ensure only the rays that have the camera and sun as end points are rendered?
Earlier quoted context omitted.
I was wondering that. I don't have anything to do with 3D graphics, but that had occurred to me. What method do they use to ensure only the rays that have the camera and sun as end points are rendered?
Bidirectional path tracing. You send rays from the sun, rays from the camera, and try to connect them. The ones that connect are the ones that get computed for illumination.
For instance: a beam hits some material and needs to reflect or worse, pass through via transparency. Another issue: If we are calculating on a per pixel basis, that means bundling multiple paths together to figure out what the weighted return will look like. How can this all be computed with any kind of efficiency without cheating?
Earlier quoted context omitted.
Bidirectional path tracing. You send rays from the sun, rays from the camera, and try to connect them. The ones that connect are the ones that get computed for illumination.
How is that even possible? The beam incidence angular calculation (and multi path dispersion) creates insane complexity that must be computed on the fly to even make sense. For instance: a beam hits some material and needs to reflect or worse, pass through via transparency. Another issue: If we are calculating on a per pixel basis, that means bundling multiple paths together to figure out what the weighted return wil…
- Trace random paths from light sources until they terminate (usually decided with Russian roulette).
- Trace random paths from the camera (usually N per pixel, or you can use more paths in noisy areas) until they terminate.
- Try to connect each point in a camera path with each point in a light path, using a simple line test. If it succeeds, that color is added to the pixel from which the camera path originated.
At least that's my understanding; I've only implemented simpler algorithms and read a bit about bidirectional path tracing.
> If we are calculating on a per pixel basis, that means bundling multiple paths together to figure out what the weighted return will look like. How can this all be computed with any kind of efficiency without cheating?
Right, we still need to consider many paths per pixel to get a high quality image. But it converges faster than most other Monte Carlo techniques.
For optimised ray tracing you don't beam the light from the camera as that has the same chance to bounce to the sun through indirect illumination as a ray from the sun has if it is going to bounce to the camera. What they are saying here is wrong or rather extremely simplified for a younger audience.
I was wondering that. I don't have anything to do with 3D graphics, but that had occurred to me. What method do they use to ensure only the rays that have the camera and sun as end points are rendered?
If the surface is refractive/reflective, recursively shoot one more ray calculating the right direction, with correctly diminished intensity and follow the same process.
Fabulous. This reminds me very much of one of my favorite Disney videos that I showed my daughter long ago. It's this clip of four very talented cell animators out practicing their Art: https://www.youtube.com/watch?v=9JK9uQNBDxQ The whole thing is whimsical while also being very educating. Really glad that Disney is keeping this kind of stuff up.
Certain things are so grossly oversimplified, they are misleading.
For example, how does sorting rays following similar direction help? The history book analogy is appalling. It might give the misguided interpretation to a kid that it is always better to sort items - e.g. before summing a few numbers, may be sorting them is a good idea, or before map operations may be sorting them will ease the task for a computer, etc.
Fabulous. This reminds me very much of one of my favorite Disney videos that I showed my daughter long ago. It's this clip of four very talented cell animators out practicing their Art: https://www.youtube.com/watch?v=9JK9uQNBDxQ The whole thing is whimsical while also being very educating. Really glad that Disney is keeping this kind of stuff up.
I actually found it disappointing, compared to some other similar Disney material I've seen earlier. It is perhaps too simple. Certain things are so grossly oversimplified, they are misleading. For example, how does sorting rays following similar direction help? The history book analogy is appalling. It might give the misguided interpretation to a kid that it is always better to sort items - e.g. before summing a few…
The big thing they were trying to get at is there are some clever tricks we can do to make these massive calculations more efficient.
For optimised ray tracing you don't beam the light from the camera as that has the same chance to bounce to the sun through indirect illumination as a ray from the sun has if it is going to bounce to the camera. What they are saying here is wrong or rather extremely simplified for a younger audience.