Intel Researchers Consider Ray-Tracing for Mobile Devices

An anonymous reader points out an Intel blog discussing the feasibility of Ray-Tracing on mobile hardware. The required processing power is reduced enough by the lower resolution on these devices that they could realistically run Ray-Traced games. We've discussed the basics of Ray-Tracing in the past. Quoting: "Moore's Law works in favor of Ray-Tracing, because it assures us that computers will get faster - much faster - while monitor resolutions will grow at a much slower pace. As computational capabilities outgrow computational requirements, the quality of rendering Ray-Tracing in real time will improve, and developers will have an opportunity to do more than ever before. We believe that with Ray-Tracing, developers will have an opportunity to deliver more content in less time, because when you render things in a physically correct environment, you can achieve high levels of quality very quickly, and with an engine that is scalable from the Ultra-Mobile to the Ultra-Powerful, Ray-Tracing may become a very popular technology in the upcoming years."

Comments

Re:prog10

[ByteSlicer]

Man, I had to google that before I got it.

Re:Inverse Moore's Law

[Slarty]

For games, at least, shadows don't need to be perfect. Neither do reflection and (especially) refraction. The goal is all about rendering something that looks plausible, not perfect (although it's a bonus if you can get it). For things like caustics, most people (and especially gamers) just aren't going to notice if the shadows or caustics or what-not are a tiny bit "off".

Current rasterization approaches use a lot of approximations, it's true, but they can get away with that because in interactive graphics, most things don't need to look perfect. It's true that there's been a lot of cool work done lately with interactive ray tracing, but for anything other than very simple renderings (mostly-static scenes with no global illumination and hard shadows), ray tracers *also* rely on a bunch of approximations. They have to: getting a "perfect", physically correct result is just not a process that scales well. (Check out The Rendering Equation on wikipedia or somewhere else if you're interested; there's a integral over the hemisphere in there that has to be evaluated, which can recursively turn into a multi-dimension integral over many hemispheres. Without cheating, the evaluation of that thing is going to kick Moore's law's ass for a long, long time.)

By the way, the claim that with a "physically correct environment, you can achieve high levels of quality very quickly" doesn't really make much sense. What's a "physically correct environment" and what is it about rasterization that can't render one? How are we defining "high levels of quality" here? And "very quickly" is just not something that applies much to ray tracers at the moment, especially in the company of "physically correct". :-)

Real time raytracing with POV-Ray

[Grard Menfin]

For those interested in real-time raytracing, the latest beta version of POV-Ray has a neat (but experimental) RTR feature. The source is now available for Windows and Unix/Linux. There also demo scenes available (and another demo scene with pre-baked textures can be found here).

Raytracing is not the holy grail of graphics

[igomaniac]

If you want to know the future of real-time graphics, look at what Pixar and other animation and special effects houses are doing. None of them are using ray-tracing except to achieve specific effects in specific circumstances. The fact is that global illumination combined with scanline renderers simply produce better pictures with less computational requirements.

Re:Raytracing is not the holy grail of graphics

[Aidtopia]

Actually Pixar has switched to Ray Tracing. Cars was ray traced [PDF]. Skimming through the whitepapers on the Pixar site, it's clear ray tracing was also used extensively in Ratatouille.

Even so, what Pixar is doing in feature films isn't particularly relevant to real-time ray tracing on mobile devices.

it's about memory, not performance or realism

[j1m 5n0w]

It's worth pointing out (and it's mentioned in the paper you cite) that the main reason Pixar hasn't been doing much ray tracing until now is not performance or realism, but memory requirements. They need to render scenes that are too complex to fit in a single computer's memory. Scanline rendering is a memory-parallel algorithm, ray tracing is not. So, they're forced to split the scene up into manageable chunks and render them separately with scanline algorithms.

This isn't an issue for games, which are going to be run on a single machine (perhaps with multiple cores, but they share memory).

Re:Inverse Moore's Law

[Slarty]

Sure, the rendering equation isn't ray tracing specific (it's a core graphics equation, independent of any one image generation method) but it's much easier to directly apply in ray tracing. There aren't many rasterization techniques that even attempt to solve it... the goal usually is just to add some ambient light effects which look like a plausible attempt at global illumination. AFAIK, even the latest, greatest game engines still stop short at something like baked-in ambient occlusion or screen-space darkening using the depth buffer. It looks cool, but physically accurate it ain't. It's much more natural to get "perfect" results in ray tracing, but that was kinda my point: getting those accurate results is pretty costly. If people don't notice the difference, why bother? Stick with the cheap approximation.

And about scalability, you're right, of course; ray tracing does scale better with scene complexity than rasterization does, and as computing power increases it will make more and more sense to use ray tracing. However, the ray tracing vs. rasterization argument has been going on for decades now, and while ray tracing researchers always seem convinced that ray tracing is going to suddenly explode and pwn the world, it hasn't happened yet and probably won't for the forseeable future. Part of it is just market entrenchment: there are ray tracing hardware accelerators, sure, but who has them? And although I've never worked with one, I'd imagine they'd have to be a bit limited, just because ray tracing is a much more global algorithm than rasterization... I can't see how it'd be easy to cram it into a stream processor with anywhere near as much efficiency as you could with a rasterizer. On the other hand, billions are invested into GPU design every year, and even the crappiest computers one nowadays. With GPUs getting more and more powerful and flexible by the year, and ray tracing basically having to rely on CPU power alone, the balance isn't going to radically shift anytime soon.

For the record, although I do research with both, I prefer ray tracing. It's conceptually simple, it's elegant, and you don't have to do a ton of rendering passes to get simple effects like refraction (which are a real PITA for rasterization). But when these articles come around (as they periodically do on Slashdot) claiming that rasterization is dead and ray tracing is the future of everything, I have to laugh. That may happen but not for a good long while.