When Will Ray Tracing Replace Rasterization?

During the past few years, ray tracing seems to have become the El Dorado of the real-time 3D world. The rendering technique sparked a peak of interest when a young researcher by the name of Daniel Pohl devoted a research project to the technology in 2004.

The reason the general public took an interest in his work is largely because Pohl chose to focus on id Software's famous Quake III, Quake IV, and Quake Wars 3D shooter game franchise. The researcher got a lot of media coverage and gamers began dreaming of a bright future in which their favorite titles would be ray traced and devoid of rasterization.

Intel soon became aware of the buzz and spotted an ideal way to justify increasing the number of cores in its processors. The company quickly started its own research program and now never misses an opportunity to remind us that ray tracing is the future of real-time 3D games. But is it, really? What technical realities lie behind the marketing hype? What are the real advantages of ray tracing? Can we really expect it to replace rasterization? We'll try to provide some answers to those questions.

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  • IzzyCraft
    Greed? You give an inch they take a mile? Very pessimistic conclusion although it helps drive the industry so hard to really complain. ;)
  • Ramar
    I'm definitely the kind of person that would prefer to lose some performance in exchange for elegance and perfection. The eye can tell when something is done cheaply in a render. I've made this argument [something most people don't even begin to grasp] that quite often we find computationally cheap methods of doing something in a game, and after time it seems to me that we've got a 400 horsepower muscle car that, on close inspection, is held together with duct tape and dreams. I'd much rather have a V6 sedan that's spotless and responds properly.

    Okay, well in real life, the Half Life 2 buggy would be a lot cooler to drive around than a Jetta, but you get the analogy.
  • stray_gator
    Great article!
  • zodiacfml
    i still like the simplicity of ray tracing and how close it is to physics/science. it is just how it works, bounce light to everything.

    there are a lot of diminishing returns i can see in the future, some are, how complex can rasterization can get? what is the diminishing returns for image resolution especially on the desktop/living room?
    ray tracing has a lot of room for optimization.

    for years to come, indeed, raster is good for what is possible in hardware. look further ahead,more than 5 years, we'll have hardware fast enough and efficient algorithm for ray tracing. not to mention the big cpu companies, amd & intel, who will push this and earn everyones money.
  • stray_gator
    aargh. start typing, then sign in to find your first words posted.
    Anyway, what I liked about this article is its being under the hood, but not related to a new product, announcement or such.
    "deep tech" articles accompanying product launches tend inevitably to follow the lines of press kits, PR slides, etc.
    Articles like this, while take longer to research, are exactly that - they are researched rather than detailing "company X implemented techniques Y and Z in their new product, which works this way, benefits performance that way and is really cool.". it gives an independent, comprehensive view of the subject, and gives the reader real understanding in the field.
  • enewmen
    The ray-tracing code on the business card was way cool. I was hoping (real-time)ray-tracing and photo-realistic rendering will come with DX11 and GPGPU offloading - this seems completely unrealistic.
    I still never read of any dedicated ray-tracing hardware, at any price. It seems the better we understand ray-tracing and it's limitations, the more cloudy the future becomes.
  • shurcooL
    Nice article. Seems to be fairly accurate.
    Ray tracing will inevtiably replace rasterization. It will just flat out look better to the human perception, when in motion, than pure rasterization, and that is all that is required.

    Heh... this article brought to you by Nvidia.
  • annymmo
    Hopefully GPGPU (OpenCL)
    will make raytracing possible.
    (Together with a huge number of processing cores per graphic card and an advanced raytracing algorithm.)
  • Inneandar
    nice article.
    I wouldn't mind having just a little bit more technical depth, but I'd be glad to seem more like this on Tom's.
  • this article brought to you by nvidia's ministry of propaganda.
    if nvidia wants to survive it must adapt and evolve. It's silly trying to persuade people about how bad raytracing is just because you're a dinosaur and don't want to acquire new know-how. Nevertheless even if nvidia is not willing to do it, there are already others who are filling the gaps.
  • hannibal
    Ok, so now with some hefty computer cluster you can render one frame in 6 hours, so it will take one day to render 4 frames. 24 frames per/s are needed, so it takes 6 days to render one second of moving picture...
    Yep we will see real time ray trasing in games in something like 20 years? (Douple the speed of computer in each year) It takes something like 15 years to calculate one frame in 0.6 second (for movie company computers) and 4-5 year more to make it 24 frames per second... If the mores law keep on kicking. For home you can expect speed like that in 5 more years? lets say 10. So summa summarum we have high guality tray trasing games 30 years from now!
    Well ofcourse Pixar has much higher need for guality, so less is needed for gaming.
    In any way nice article! And in real life some sort of tray trasing can be seen sooner, but photorealistic computing is still far far away... pity I will be in pension or dead before I see it...
    Lets face it. What do we have today> Current cards using rasterization playing much more lifelike games on much larger monitors. The closer we get to "itll play Crysis", the more the boundaries move, and puts it just that much closer to Ray Tracing.
    Great job Fredi, and tho some will deny what its going to take to get RT RT, you painted it as well as Ive seen. As for more in depth,if the article was too finely explained, the overall picture may have been lost, as seen by some comments.
    I cant find the link I posted awhile back in the forums about Lexus? having a full time raytracer for their designing, but its still slow, and requires over 320 cores which are designed for this kind of work, not just a simple x86 cpu, so yea, we are aways off before anything real happens.
    Once again, excellent article
  • downer88
    Wouldn't real time ray tracing need many many more CPU cores than the four barely used today, and would get rid of the graphics card? If so, its too big a leap for anytime soon.
  • TwoDigital
    I won't go quite so far out as Hannibal... keep in mind that Pixar is largely these days rendering for imax-quality images (~12,000 x 8700.) It may indeed take 20 to 30 years before you're playing Crysis on a desktop monitor that's that dense. In the mean time, you will see raytracing come to desktop games (so long as people keep asking for it) more in a 1920 x 1080 version with low quality settings at first for your higher framerates.
  • gamerk316
    More or less what I figured. Ray tracing has its benifits, but I was always a bit concerned at the data structures and how they were designed. The fact is, regardless of how much better it works, if its too hard to manage to code without clear and visable benifits, then devs won't use it.

    Rasterization is still the better method. Besides, a decade ago, Doom3 proved you could do dynamic shadows in rasterization, which skeptics thought was too costly to perform (or downright impossible). Reflections will eventually follow.
  • Parrdacc
    Awesome article. Really enjoyed reading it. However, based on current technology, well the type that us regular joe's can afford, I do not see this as being very economical for companies. That and based on my limited understanding; the human eye can only see, or should i say distinguish, so much as it is to begin with (color hues and whatnot)that it would not make a whole lot of sense to go to far with this as at a cetain point it would not make a difference to our senses anyway.

    Add on top of that the processing power needed to reach such levels at this time is just not economically smart. In time when average people can afford a system capable of rendering such games then it would make sense but only to the point in which our senses can actually distinguish whats on the screen.
  • Lighting effects makes all the difference. If the lighting and shadows are not convincing to the eye isn't "fooled" and the scene isn't convincing.
    Think of Film Noir and the very effective use of darkness an shadows. What you don't see contrasts what you do.
    Remember the brighter the light source the DARKER the shadow.
    If you are in bright sunlight (Fallout3) the shadows casts by objects and characters should be BLACK to you. This is because your iris is closed because of the sunlight. IT seem that something so simple is hard to pull off with rasterized rendering.
  • megamanx00
    Perhaps one day, but not anytime soon. Despite what Intel says, Larrabee won't do it either. I don't expect to see them ray tracing Crysis anytime soon.
  • thiswillkillthat
    The thing is that the standard you hold an image to is also dependent on your standards. I work with physically accurate rendering programs on a nearly daily basis for the purpose of creating architectural visualizations. To my eyes, rasterization looks like crap. Raytracing is an improvement, but still hardly ideal. People aren't used to the quality of raytracing, let alone metropolis light transport, so they're happy with rasterization. If ray tracing were the standard, rasterized images would be considered to be subpar.
  • cablechewer
    If processing power keeps growing and caches keep increasing (specifically level 2 and 3 caches that feed all the cores of a single chip) might we not reach a point where everything to render a frame from a scene will fit on a single chip?

    Over the last few years resolution has also been increasing which increases processing demands. Will we hit (or have we already hit) a point where increased resolution offers diminishing returns? For example the density of pixels on my current monitor works out to about 57 pixels per centimeter. How much higher will this go in the future?

    What I am wondering is whether resolution and pixel density increases will fall off while processing and cache increases continue. That might leave us in a very interesting place in a decade and might make ray tracing more practical.

    Lastly I heard that ray tracing offered benefits for physics engines and collision detection. Will that mitigate the complexity and processor requirements as physics plays a greater role?
  • warezme
    Great Article, descriptive, informative with perfect fact filled examples. Awesome work Fedy.
  • kittle
    Neat article.

    I agree raytracing isnt ready for realtime graphics - but on the differences between rasterization and ray-tracing you missed one key point: Polygons.
    In a pure raytracing environment you essentially have infinite polygons because all the surfaces are mathematicly defined, vs being a collection of triangles in the rasterization world.

    Take the "simple" sphere. In the raytraced world, you essentially have 3 sets of values: the center point of the sphere, its radius and an optional scaling value.
    In the rasterization / polygon / triangle based world, you have potentially large number of triangles needed to render the sphere. Yes there are various tricks used to make the curved surface 'look' smooth - but they are just that: tricks.
  • knowom
    It'll all be sorted out in the future one way or another gpu's are becoming more parallel, memory bit rates are gradually increasing, and memory densities are increasing rather dramatically. Additionally are becoming more parallel as well plus system memory and storage mediums are bigger and faster as well. It's only a matter of time.