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Another really fun Cray comparison: Turner Whitted (“father of ray tracing”) is rumored to have speculated some time back when he first published on ray tracing

by dahart 3y ago

Another really fun Cray comparison: Turner Whitted (“father of ray tracing”) is rumored to have speculated some time back when he first published on ray tracing that in order to do real time ray tracing, you could put one Cray supercomputer per pixel out in the desert, each one with a single colored light, and view it from an airplane, and that would be roughly enough compute to achieve real time. A 4090 today is roughly 500,000 times faster, which means we now have achieved one Cray per pixel (!) for an 800x600 image (smaller than images today, but maybe a bit larger than the average image size in the late 70s).

RicoElectrico 3y ago
To be honest our real-time RT works only because we're "cheating" with denoisers working in spatial and temporal domain.
- corysama 3y ago
  Sure, to get Cyberpunk 2077 at 4K 60FPS, we cheat like hell. But, a scene from 70s ray tracing research at 800x600x24 fps on a 4090 doesn’t need to cheat much.
  - ryao 3y ago
    Does cyberpunk 2077’s overdrive mode remove the cheating or is it still cheating beyond the use of a denoiser?
- dahart 3y ago
  In a way, yes, partly because we’re rendering typically larger images now (1080p is 4x larger than 800x600), but also because the image quality standards are very high, and because scenes are enormous compared to a pair of spheres and a checkerboard plane with a single light, because games don’t get to spend the entire frame budget on rays, and because we’re using a lot more stochastic sampling now using path tracing than what Turner Whitted did. We do get the 500,000x relative to Cray, and denoising effectively adds another x-factor on top of that, and that’s what it takes to get today’s games up to passable real time ray tracing. On the other hand, genuine real-time ray tracing without denoising has been possible for a long time for toy scenes outside of games, it all depends on what goal posts we’re talking about exactly, right?
- deleted 3y ago
  [deleted]
dekhn 3y ago
I have not... heard that idea before. Instead, I heard "reality is just 100 million polygons per second" (Jim Clark?), implying that if you can do ray tracing at a high resolution and frame rate, you can fool somebody's optical nerves into thinking they are looking at reality (ignoring the difference between pixel screens and the physics of how human vision actually works). Does anybody have a reliable link to the Whitted quote?
- dahart 3y ago
  My source for the story is indirect, via Steve Parker, who’s worked with Turner. https://www.youtube.com/live/LUFp6sjKbkE?si=8vcxo-Vp8oeRUnob https://www.youtube.com/live/LUFp6sjKbkE?si=8vcxo-Vp8oeRUnob Scrub to 3:52:19 for the Turner Whitted story. BTW, mostly unrelated, but scrub that video to 5:47:10 for an amazing talk by Ivan Sutherland (“father of computer graphics”) that is not about graphics (he politely refuses to talk about graphics anymore :P), but about the active research he’s been doing (at 85 years old) into Single Quantum Flux circuits (an alternative to CMOS). Also- Jim Clark at 4:48:40 Jim’s idea you mention is still correct & compatible with Turner’s idea. Jim’s point is that we only need to render finite pixels. You might need an x-factor more triangles than pixels because of sampling and depth complexity and secondary lighting, so 100M polys is probably in the ball park, as long as we can quickly pick the right 100M polys in real time… In a way, Turner was talking about a lower bound, while Jim is talking about an upper bound, albeit slightly different things but they are similar, both relate to how much compute is needed for real time rendering.
  - dekhn 3y ago
    Thanks for the timestamps. Great to see Ivan breaking ground in another area, his contribution to early graphics and interactive computing is still amazing today.
  - jazzyjackson 3y ago
    Offtopic but FYI youtube share links now come equipped with a tracking parameter (si=). You can safely leave the querystring behind if you don't want Google to associate your google account with other places you post online.

by dahart 3y ago

RicoElectrico 3y ago

To be honest our real-time RT works only because we're "cheating" with denoisers working in spatial and temporal domain.

corysama 3y ago
Sure, to get Cyberpunk 2077 at 4K 60FPS, we cheat like hell. But, a scene from 70s ray tracing research at 800x600x24 fps on a 4090 doesn’t need to cheat much.
- ryao 3y ago
  Does cyberpunk 2077’s overdrive mode remove the cheating or is it still cheating beyond the use of a denoiser?
dahart 3y ago
In a way, yes, partly because we’re rendering typically larger images now (1080p is 4x larger than 800x600), but also because the image quality standards are very high, and because scenes are enormous compared to a pair of spheres and a checkerboard plane with a single light, because games don’t get to spend the entire frame budget on rays, and because we’re using a lot more stochastic sampling now using path tracing than what Turner Whitted did. We do get the 500,000x relative to Cray, and denoising effectively adds another x-factor on top of that, and that’s what it takes to get today’s games up to passable real time ray tracing. On the other hand, genuine real-time ray tracing without denoising has been possible for a long time for toy scenes outside of games, it all depends on what goal posts we’re talking about exactly, right?
deleted 3y ago
[deleted]

dekhn 3y ago

I have not... heard that idea before. Instead, I heard "reality is just 100 million polygons per second" (Jim Clark?), implying that if you can do ray tracing at a high resolution and frame rate, you can fool somebody's optical nerves into thinking they are looking at reality (ignoring the difference between pixel screens and the physics of how human vision actually works). Does anybody have a reliable link to the Whitted quote?

dahart 3y ago
My source for the story is indirect, via Steve Parker, who’s worked with Turner. https://www.youtube.com/live/LUFp6sjKbkE?si=8vcxo-Vp8oeRUnob https://www.youtube.com/live/LUFp6sjKbkE?si=8vcxo-Vp8oeRUnob Scrub to 3:52:19 for the Turner Whitted story. BTW, mostly unrelated, but scrub that video to 5:47:10 for an amazing talk by Ivan Sutherland (“father of computer graphics”) that is not about graphics (he politely refuses to talk about graphics anymore :P), but about the active research he’s been doing (at 85 years old) into Single Quantum Flux circuits (an alternative to CMOS). Also- Jim Clark at 4:48:40 Jim’s idea you mention is still correct & compatible with Turner’s idea. Jim’s point is that we only need to render finite pixels. You might need an x-factor more triangles than pixels because of sampling and depth complexity and secondary lighting, so 100M polys is probably in the ball park, as long as we can quickly pick the right 100M polys in real time… In a way, Turner was talking about a lower bound, while Jim is talking about an upper bound, albeit slightly different things but they are similar, both relate to how much compute is needed for real time rendering.
- dekhn 3y ago
  Thanks for the timestamps. Great to see Ivan breaking ground in another area, his contribution to early graphics and interactive computing is still amazing today.
- jazzyjackson 3y ago
  Offtopic but FYI youtube share links now come equipped with a tracking parameter (si=). You can safely leave the querystring behind if you don't want Google to associate your google account with other places you post online.