NVIDIA Shows Interactive Ray Tracing on GPUs

We just received some interesting news out of SIGGRAPH 2008 that we thought many of you would be very interested in. If you recall, one of the capabilities Intel is touting in regard to their upcoming Larrabee architecture is the ability to perform real-time ray tracing. In the graphics space, ray tracing is a technique used to generate an image by tracing the rays or paths of light as they bounce through and around the objects in a scene. When done right, ray tracing can produce photorealistic imagery because shadows are cast correctly, water and other materials show proper reflections with correct coloring, and lighting in general just looks more realistic. The problem with ray tracing is that the algorithms necessary for producing photorealistic imagery are very complex and require much more compute power than is available in today's PCs, if the imagery is to be rendered in real-time, at a high enough frame rate to produce fluid motion, i.e. for gaming.

To date, a number of real time ray tracing projects have been shown on the PC. Intel's Daniel Pohl, for example, has showcased customized versions of Quake 3 and Quake 4 running on Intel hardware that use ray tracing to great effect and ATI has recently shown ray tracing demos running on Radeon HD 4800 series hardware at their Cinema 2.0 event. But today, it's NVIDIA's turn.

 
   
NVIDIA's GPU RayTracing Demo In Action

During SIGGRAPH 2008 in Los Angeles NVIDIA is demonstrating a fully interactive GPU-based ray tracer. The demo is based purely on NVIDIA GPU technology, and according to NVIDIA the ray tracer shows linear scaling rendering of a complex, two-million polygon, anti-aliased automotive styling application. Screenshots from the actual demo are shown here.

 
   
NVIDIA GPU Ray Tracing at 2560x1600

At three bounces, performance is demonstrated at up to 30 frames per second (fps) at HD resolutions of 1920x1080 for an image-based lighting paint shader, ray traced shadows, and reflections and refractions running on four next-generation Quadro GPUs in an NVIDIA Quadro Plex 2100 D4 Visual Computing System (VCS). Some of these screenshots, however, were taken with the resolution increased all the way up to 2560x1600. Frame rates at that resolution weren't available though.

If we can speculate for a bit here, let's assume that the next-gen Quadros NVIDIA is using for the demo are based on the company's GTX 200 series GPU architecture. That means, potentially, a 3-way GeForce GTX 280 SLI configuration may offer approximately 75% of the performance of Quadro Plex 2100 D4 VCS being used in the demo. If history is an indicator, sometime within the next 18 months or so, NVIDIA is likely to double the performance of their current GPUs. So, by sometime next year or maybe in the early part of 2010, we'll likely have the necessary horsepower in a high-end gaming PC to handle real-time ray tracing with adequate performance for fluid motion. Over the next few months to a year, expect to hear much more on this front.

Looks pretty dialed there for sure. Love how the ray traced stuff all looks so accurately lit and natural. Check out the reflections too...

That Quadro Plex they are running that on probably costs, what, like $15,000-20,000?!?

That's pretty cool, but why don't they do this kind of stuff with sound? We need sound cards that calculate the way the sound of a gunshot bounces off the 3D structure of the room you are in, or the nearby buildings or something like that.

This is "barely" ray traced - three bounces is no where near what you need for good looking ray tracing. The shadows are hard, there's no inter-reflections - I could go on. Unless you are going to really have alot of rays (30+ to 300+s) you're not going to get to cinema quality and you're just really cutting corners to meet those fps performance claims. Nice try.

Well hello there, Andyzee! Welcome and thanks for that tidbit of info too. Good stuff!

Awesome tech. Be cool to see what this adds to graphics in games in a few yrs

Fold On!!!!

warlord:

Awesome tech. Be cool to see what this adds to graphics in games in a few yrs

Fold On!!!!

Thats what I said about it a few years ago

OMG on the fourth pic that shows the reflections on the right side of the car door there's a nude woman sitting in the area right under the mirror

Totally don't see the naked chick

rofl got ya :)

LoL got ya......... Wow that was quicker than I thought somebodied be studieing the door looking for some boobs :)

>> "performance is demonstrated at up to 30 frames per second (fps)"

"Up to"? I would think it's going to need to stay consistently above that mark before it's useful for an actual game.

Now take a look at all the pictures again, but this time drop 4 hits of LSD, then tell me what you see. You only see what your mind interprets... By the way I see pixelization on the door of the 4th pic.

rodriro:

Now take a look at all the pictures again, but this time drop 4 hits of LSD, then tell me what you see.

Ooooohhh now I see the naked chick.

Daniel Pohl showed an 8 core box where he was bouncing the rays until the color changed by less than a certain percentage. He was getting 60fps at something like 1024x1024, maybe a little higher. This implies what has been shown time and again that GPU's don't get great performance with raytracing despite their insace floating point power. The best raytracing power has been on Cell processors, however, since they are a hybrid and have just about the perfect setup for raytracing.

Intels new "GPU" they are creating is basically 48 simpler CPU cores with 4 concurrent threads and 4 Floating point units each. I believe it was designed to do raytracing well, and can do current rasterizing techniques as well. Nvidia and AMD need to design chips like this or the cell. We really do have the technology to do raytracing on PC hardware now, it's just a matter of putting the right hardware together.

I want in game raytracing. that will be nice

Lev Astov,

SoundBlaster Live! cards have been kind of doing that for years, but I believe it only emulates a box shaped room in a kind of half-ass way. However, in professional applications, there is software that will allow you to emulate the acoustics of a modeled environment, and it could probably be applied to sound cards. The differences would be very subtle, though. I would first want the card manufacturer to invest in a proper DAC before working on those kinds of enhancements.

Thank you Lev! I've been asking this for years. Several years ago when graphics cards started to plateau, I wondered when gamers would start expecting more sophisticated sound. Apparently, the demand isn't there...at least no company has tried to solve it. How stupid is it when I'm in a concrete bunker and I can hear, clear as day, someone outside the bunker rummaging around in the grass? Totally lame. I don't think the average gamer understand or appreciates that part sound plays in the immersion experience. The only advance in gaming audio in the last 10 years (besides 5.1 sound) is adding reverb when you race through tunnels.

Fail.

Neither CPUs or GPUs are suited for ray tracing - it's not a compute problem - it's a memory bandwidth problem. As the ray scatter and bounce around the scene all the shader programs that need to run don't have the data on cache, so they have to fetch it and there's not enough bandwidth to do that, so the compute is underutilized. All these Intel and Nvidia demos constrain the amount of ray bounces so that they don't become memory bound - but because of that they're not really ray tracing. We already have plenty of compute in CPUs and GPUs, but that's not going to make ray tracing possible for gaming unless the problem is looked at differently.

I think andyzee is describing photon mapping, which is above and beyond simple ray tracing. Ray tracing (from the eye, which I believe to be the standard usage) does not naturally produce soft shadows or diffuse interreflection (which I assume he meant, because interreflection is plainly visible up to the stated three bounces). Adding more bounces to the rays wouldn't add much visually, excepting the depth to which you could trace between reflective surfaces (e.g., how many reflections you'd see in facing mirrors).

Thanks 3vi1, those are my thoughts exactly. I do appreciate graphical realism, but if they can't be made smooth and playable (average 60+ fps, 30 fps min.) then the good graphics aren't worth the time and effort.

I had recently watched a "3D" movie at the theater with my daughter; and the action sometimes moved to fast you to identify what is on screen. I don't think that this is an issue with the 3D effect of the film, but more to do with lacking enough frames in-between the shots to make out which direction the motion is moving in. It made for several disorienting seconds of the film but left a disfavorable impression with both of us.

yeah when graphics engines and hardware get to this point on a normal basis we'll be in for something until you get a job making six figures a year and I'm talking more than 100000 especially after this presidential election because the tax rate will go up rofl and it gets dwon to a mere 1000 dollar video cards the graphics industry (talking about gameing developement) won't touch it or until they actually get dual triple graphics cards working to at least a 75% ratio and you can afford two decent graphics cards that can do it for less than 1500 this is a pipe dream for now although I wish it was'nt true.

The problem with the nvidia devices for raytracing is that they dont cope with random memory access patterns very well - usually incur a 600 cycle latency on a global memory fetch. Not exactly conducive for ray tracing where you need to access scene object data in a largely random pattern.
I agree with andyzee: to progress with ray-tracing as a viable rendering alternative we need to rethink the whole way raytracing is implemented or optimize the acceleration structures in such a way to suit nvidia hardware.
For the quality of image you get I really think it is worth doing.