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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?
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?
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.
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.
XML is like violence. If it doesn't solve the problem, use more.
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.
"However fast you get at ray tracing, you can instead use that power for rasterization and do far far more."
Not when you are real time rendering the graphics to be integrated on the fly along side real time light vectors flying at the retina. Think pokemon go, without the phone, or the screen, and with the pokemon actually sitting on your counter with it's legs hanging down.
The first thing to understand is that the Nvidia and MS press releases are complete crap. Oh it "works". The UE4 Star Wars thing is real enough. It's also running on $12,000 worth of GPUs at 30fps in 1080p, and is only partially raytraced.
Now does this mean realtime raytracing isn't here? Well the answer is no, it is here. The game Claybook is entirely raytraced, unlike the DirectX demos. It's in early access and runs on nothing more than an Xbox One or PS4, and does so at 60 frames per second. Here's the trailer: https://www.youtube.com/watch?... Now THIS is possible because graphics programmers have gotten quite clever over the years. The cleverest bit is called signed distance fields. This can be thought of a volume of points, or boxes, that all store the nearest distance to a solid "surface". Going through this structure allows you to raytrace very very quickly, as you know how much empty space you can skip each time without hitting anything. And since this data is relatively small for each point it doesn't use up a lot of memory either. It's so fast and low memory you can run a demo in your browser here: https://www.shadertoy.com/view...
Obviously there's a bunch of other clever programming going on in Claybook and other titles. But SDF's are the biggest thing to understand. That and that the MS Raytracing API is totally uninteresting from a performance perspective. In fact it's rather awful.