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Ray Tracing Is No New Thing

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Re: Ray Tracing Is No New Thing

#31

Post by maaark »

arayh wrote: post #5

Gamers have long been clammering about how they can't wait until in-game graphics match those of pre-rendered cinematics (that said, a lot of cinematics these days are no longer pre-rendered). Ray tracing is such an expensive operation. According to this quora, it took 29 hours to render a single frame of "Monsters University": https://www.quora.com/How-long-does-it-take-to-render-a-Pixa... We're probably nowhere clo…

We've also long since passed the point where games have pre-rendered scenes that could have been rendered in-engine on high-end hardware.

The only tip-off I had that (some of) Nier Automata's cutscenes are pre-rendered was the drop to 30fps...

Re: Ray Tracing Is No New Thing

#32

Post by bni »

Im an Amiga fan but in what way is the Juggler demo relevant here at all? Ray tracing and storing the 2D result, was surely done much earlier on workstations from SGI, Sun etc

Re: Ray Tracing Is No New Thing

#33

Post by pcwalton »

rollulus wrote: post #7

I'd say that it is rather obvious that ray tracing is not a new thing, since it is simulates how light physically behaves. I consider this 3d rendering as a spectrum: rasterization requires little computation but has little to do with physics. Ray tracing is what requires a lot of computation and has everything to do with physics. Somewhere in between are hybrid methods: rasterization with ray tracing components adde…

Rasterization and raytracing are formally equivalent in a sense. You should be able to algebraically rearrange ray/triangle intersection tests performed in raytracing to get Pineda rasterization. So I don't really see one as more physical than the other. Rather the difference is that rasterization starts with each triangle and determines which rays intersect it, while raytracing starts with each ray and determines which triangles intersect it.

Re: Ray Tracing Is No New Thing

#34

Post by mgkimsal »

bni wrote: post #32

Im an Amiga fan but in what way is the Juggler demo relevant here at all? Ray tracing and storing the 2D result, was surely done much earlier on workstations from SGI, Sun etc

i'd say it's somewhat relevant in that it popularized the idea to a new generation of folks (like me) who'd never heard of it before. spent hours with pov-ray as a kid (well... minutes, then hours waiting). didn't know at the time it wasn't 'new' (it was 'new' to me), but also AFAIK there were no other moderately affordable home computing systems where this was possible. maybe it was a thing on ms-dos clones of the late 80s and I just missed it there?

Re: Ray Tracing Is No New Thing

#35

Post by kabes »

arayh wrote: post #5

Gamers have long been clammering about how they can't wait until in-game graphics match those of pre-rendered cinematics (that said, a lot of cinematics these days are no longer pre-rendered). Ray tracing is such an expensive operation. According to this quora, it took 29 hours to render a single frame of "Monsters University": https://www.quora.com/How-long-does-it-take-to-render-a-Pixa... We're probably nowhere clo…

Actually, even till late 2000s most of pixar movies were based on rasterization (reyes). So you don't necessarily need ray tracing for that.

Re: Ray Tracing Is No New Thing

#36

Post by GuB-42 »

rollulus wrote: post #7

I'd say that it is rather obvious that ray tracing is not a new thing, since it is simulates how light physically behaves. I consider this 3d rendering as a spectrum: rasterization requires little computation but has little to do with physics. Ray tracing is what requires a lot of computation and has everything to do with physics. Somewhere in between are hybrid methods: rasterization with ray tracing components adde…

Rasterization has just as much to do with physics as raytracing. They can both get you a correct solution to the rendering equation (i.e. be physically correct) if you wait long enough, or get you an approximation of it in a reasonable time scale.

For example if all you need are shadows cast from a point light source, a rasterization technique like stencil shadows will give you the same exact result as simple raytracing, and neither will be physically correct.

It is just that depending on your rendering time budget, some things are better done with rasterization and others are better done with raytracing. Real time engines, with simplified models typically work better with rasterization, while precalculated scenes, with more realistic models work better with raytracing.

Re: Ray Tracing Is No New Thing

#38

Post by toolslive »

ctrl-j wrote: post #29
toolslive wrote: post #26

Earlier quoted context omitted.

Radiosity would qualify better as `based on physics` than ray tracing, but can't do things like mirrors. I could live with classifying ray tracing as `geometry based`, like Newton studied mirrors. (You could do something that uses ray tracing to determine what's visible and what isn't and radiosity to determine the colour, but that's an entirely different story).

What is your qualm with calling ray-tracing physically based? Don't most models even include transmissivity and refraction? I mean, unless you're expecting them to calculate absorption/re-emission at every bounce... It still seems pretty "physical" to me.

Here you're using geometrical optics which models is a narrow beam (ray) which is idealized as a line. It all becomes simple vector math form there onwards.

However, Physics knows since the end of the 18th century light is a wave.

https://en.wikipedia.org/wiki/Young%27s_interference_experim...

It's not that the model breaks down only in extreme conditions (like Newton's laws of mechanices), but in day to day situations as well.

I think that's the essence of my qualm.

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