Ask Slashdot: How Did Real-Time Ray Tracing Become Possible With Today's Technology?

dryriver writes: There are occasions where multiple big tech manufacturers all announce the exact same innovation at the same time -- e.g. 4K UHD TVs. Everybody in broadcasting and audiovisual content creation knew that 4K/8K UHD and high dynamic range (HDR) were coming years in advance, and that all the big TV and screen manufacturers were preparing 4K UHD HDR product lines because FHD was beginning to bore consumers. It came as no surprise when everybody had a 4K UHD product announcement and demo ready at the same time. Something very unusual happened this year at GDC 2018 however. Multiple graphics and GPU companies, like Microsoft, Nvidia, and AMD, as well as other game developers and game engine makers, all announced that real-time ray tracing is coming to their mass-market products, and by extension, to computer games, VR content and other realtime 3D applications.

Why is this odd? Because for many years any mention of 30+ FPS real-time ray tracing was thought to be utterly impossible with today's hardware technology. It was deemed far too computationally intensive for today's GPU technology and far too expensive for anything mass market. Gamers weren't screaming for the technology. Technologists didn't think it was doable at this point in time. Raster 3D graphics -- what we have in DirectX, OpenGL and game consoles today -- was very, very profitable and could easily have evolved further the way it has for another 7 to 8 years. And suddenly there it was: everybody announced at the same time that real-time ray tracing is not only technically possible, but also coming to your home gaming PC much sooner than anybody thought. Working tech demos were shown. What happened? How did real-time ray tracing, which only a few 3D graphics nerds and researchers in the field talked about until recently, suddenly become so technically possible, economically feasible, and so guaranteed-to-be-profitable that everybody announced this year that they are doing it?

Comments

It isn't out of the blue

[kiminator]

The short answer is that it isn't brand-new. As the article mentions, nVidia has been doing real-time ray-tracing demos for about a decade. Various tricks and approximations are used to make this a reality. Game developers have largely shied away from it because similar results can be achieved with typically better performance using other methods.

This announcement, particularly with the involvement of Microsoft, indicates that the companies finally feel that the technology is mature enough to actually be used in a game. My guess is that it will likely still be some time before it is put to use. The fact that it was announced at the same time likely indicates that the three companies have been working together for some time behind closed-doors to agree upon the DirectX Raytracing API.

Terminology

[B.Stolk]

Be careful with your terminology.

Real Time Ray Tracing with one primary ray and one shadow ray for each pixel, was viable last year as well (at 1080p.)
But this will not render indirect light, thus no Global Illumination.

You may be referring to Real Time Path Tracing, where you need to shoot a lot of rays for every pixel.
This is currently not possible, and also not possible in this year's GDC demos: I think most of the demos were hybrids (rasterizing+tracing), and definitely not full Global Illumination.

Ummm, this isn't too shocking

[Anonymous Coward]

Real time ray tracing was a topic since I was in college 20 years ago. A lot of PhD students have done their research. Algorithms optimized. Hardware advancing. Futurists at major corporations (fancy name for people responsible for monitoring tech) saw hardware evolving.

So Microsoft probably saw that it was going to be viable in 5 years (or whenever) in 2013. They probably starting developing an API in conjunction with major hardware manufacturers. So they all worked together to bring ray tracing to the masses eventually.

Now all this work is paying off and consumers get the end product.

This is no different than major corporations using augmented reality to validate construction designs. Ya, they are doing that atleast in labs. Take the 3D model as built and validate that it is as built. Or quickly look at something in the real world and figure out where the 3D model data is and figure out in a second what vendor supplied the broken part. Ya, this stuff is happening!

Well, not all of a sudden...

[Junta]

Demos of real time raytracing have dated back to 2009 or earlier, albeit with various limitations. Raster based rendering is faster and going to raytracing means much better lighting, at the expense of some resolution/geometric detail/hardware requirements.

I think what is being seen is that we've been well beyond the point of diminishing returns as far as raster can reasonably get in terms of better quality. Sure, we can cram more and more polygons and sure we can raise the bar to 4k resolution, but the bang for the back is small. Given that situation, video card market has an issue, they need to do demand generation.

So pushing 4k for gaming helps, and 8k would be nice, but it's just really hard to tell the difference at this point.

If that's a hard sell, then VR certainly can knock things back if it gets traction. With wider FOV, stereoscopic rendering, and optimal experience being at least 90Hz, that would certainly deliver. However, as much as I am a fan of it, it's far from a given that VR is ever going to be large enough to drive adoption. at volumes that can sate the business needs of the GPU vendors.

So raytracing is a third option to make best of breed graphics card noticeably struggle with something that's very visually apparent. Suddenly the market content with status quo of ever refined raster graphics simply must make the leap to have some marketable advancement.

The people pessimistic about any such advancement just continuously have their expectations calibrated to how fast it can perform raster graphics. Raytracing does mean having to step back, but we have enough headroom to take the hit.

It is HYBRID, not full Realtime ray tracing

[Anonymous Coward]

It is using rasterization for the scene, and then hybrid ray tracing for the reflective, shadow, and opacity components were it applies. This is not true ray-tracing, but rather another rendering "trick" to optimize for speed. Most of our rendering for games today is approximations, because it is good enough. Same thing here.

Raster 3D Graphics seem to be tapped out

[rsilvergun]

Remember the jump from the SNES/Genesis to Playstation/Saturn? How about the first time you saw a Dreamcast game? Those were big leaps. But PS2 to PS3? If you'd been paying PC games you'd seen stuff on par with PS3. And PS3 to 4 was hardly a leap at all.

The trouble is modern graphics have gotten _hard_ to make. Pixel shaders are a bitch. They're too labor intensive. What's needed is something that lets you do great graphics with less man hours and fewer bugs. If ray tracing isn't gonna do that then it might as well be PC's answer to 3D TVs. Especially if it's only kicking out 30 FPS.

...and clever Algorithms

[Roger W Moore]

According to this video it is not just more powerful hardware but also that they came up with the idea to use only a fraction of the rays normally required and to then used a power denoise algorithm to generate the final image.