Next gen lighting technologies - voxelised, traced, and everything else *spawn*

Discussion in 'Rendering Technology and APIs' started by Scott_Arm, Aug 21, 2018.

  1. Ike Turner

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    I'm totally in agreement with you here.

    Some thoughts on the subject by the Graphics Programming Lead at NetherRealm Studios (Motal Kombat and Injustice games):

    https://deadvoxels.blogspot.com/2018/08/some-thoughts-re-siggraph-2018.html


    More a the link
     
    #101 Ike Turner, Aug 23, 2018
    Last edited: Aug 23, 2018
  2. iroboto

    iroboto Daft Funk
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    I get where your argument is going; some considerations:

    [​IMG]

    According to Jensen there are 3 separate processors on this chip
    The Turing SM containing 3 more TF of power than a Titan X.
    The RT Core that can produce 10 Giga rays/sec
    The Tensor core at 110 TF at FP16
    To put things into perspective. Titan X is 12B transistors. Turing is 18.9B

    His only fallacy here is to compare the whole 1080TI vs _just_ the RT Core in ray tracing ability. As we have no way to measure how that would work...
    except he provided some context to his words:
    [​IMG]

    With the Light green bar being RT.
    Dark green bar being Rasterization
    S being shading.

    You said his claim was, before Turing, RT was impossible. In the story that Jensen tells, he is essentially saying, DGX (4 Voltas) rendered the star wars vid at 55ms, approximately $66K worth of hardware.

    A single 2080TI did it faster at a sub $1000 price point.
    1080TI coming in at 308ms.

    I don't think his claim is completely out to lunch here here. If these are the benchmarks, Turing has accomplished something that could not previously be accomplished when you consider the cost points.
     
  3. Ike Turner

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    More points to ad to the discussion:

    - What Jensen publicly says is often false or misleading or GREATLY exaggerated. Case in point during the same keynote he claimed 3 things that are factually false: Nvidia invented TAA (False), Nvidia Invented the GPU (False), Nvidia invented the first RT GPU (False). So what ever he says about anything should be taken with a heavy dose of salt. But then again some well known bozo recently said that "Truth it not the Truth" apparently..so maybe that's that.. Anyway that has always been Jensen thing since forever. Met him twice in the early 2000s..charming dude but full of hot hyperbolic s...
    - Star Wars Reflections demo didn't absolutely "require" 4 Volta's at the time of GDC and it was obviously optimised since then. So yeah it now runs on one Turing GPU (he never specified the SKU)..but it most probably doesn't need 4 Volta's either.


    Turing is a great friggin good GPU. But in terms of RT & the usability of this feature for games today it's the equivalent of the T&L implementation on the GeForce256 (the supposedly first GPU ever according to Jensen..).

    Just don't take any company's marketing word for granted (especially Nvidia who has build it's public image with grand claims of supposedly earth shattering groundbreaking Guiness Book records setting inventions..)
     
    #103 Ike Turner, Aug 23, 2018
    Last edited: Aug 23, 2018
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  4. DSoup

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    Thiis where I am. The conventional GPU is stellar; a great improvement over the GTX10xx but the rest is just selling the promise of what the technology will deliver in x number of generations when a) more widespread, and b) more refined.
     
  5. Clukos

    Clukos Bloodborne 2 when?
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  6. iroboto

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    You’ve done a great job establishing precedent here.

    But to the original commentary, in a few months time we will have real benchmarks on DXR titles and there will be comparisons of AAA titles of pascal vs Turing. If the performance gap is massive then how valid is your original post of DXR can still be supported on non RT hardware.

    You’ve made a strong argument that marketing could be entirely BS and that we shouldnt trust it. But End of the day we as consumers only play the end product. We can go to the moon to look for reasons why pascal perhaps will not perform as well as Turing, but end of the day is how those games perform with RT on.

    And that’s the crux of my argument, we can debate and question marketing information, but Real game benchmarks will be the ultimate end game for this discussion. Unless pascal is able to keep up with Turing in RT applications, your points will invalidate on their own.
     
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  7. Lalaland

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    Ok so we have some actual numbers rather than "look this bar is over twice as big on the bestest scale" marketing guff. So they're saying in this slide that for evaluating N Samples Per Pixel (?) Turing up to five times as fast, I'm pretty unfamiliar with RT beyond the basics but is SPP a std perf measure for RT? I understood RT to be about rays drawn from light emitters and bounces (GigaRays) but why are they talking about SPP? Is this related to a particular RT implementation or does each pixel after the various Rays are calculated get a sample table that says say "4 Rays from Source A + 2 Rays from Source B = Blue light"?
     
  8. Magnum_Force

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  9. pharma

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    Thanks for the link. It does reveal much about the issues/tradeoffs involved in ray-tracing and helps bring together what Nvidia hopes to achieve with parts of their new architecture.
     
  10. imerso

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    While I do agree that demoscene productions are awesome (and I even have two releases myself, one of them being real-time ray traced), I do not agree that they can be directly compared to what DXR does. DXR traces polygon soups, which is much harder and intensive than sphere-tracing primitive geometries like spheres and cubes. There is a very important difference here. =)
     
  11. OCASM

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    DXR can be used for sphere tracing with custom intersector shaders.
     
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  12. imerso

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    Yes, certainly. I was implying that we can't compare performance of sphere-tracing primitives against freely modeled big polygonal scenes. Anyway, as is already agreed, the (sort of) standardization brought by DXR will allow more devs to bring new ideas, and we will see a faster progress now. I think that in a few years ray tracing will become the standard and we will never look back to pure rasterization (or I hope so, at least).

    Eventually we'll switch to ray traced voxels and eliminate polygons, I guess.

    This all sounds so awesome, much like when the industry switched from CPU only to the first GPUs!
     
  13. BRiT

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  14. Psycho

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    Except that the above linked '5 faces' IS raytracing polygon soups...
     
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  15. pharma

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    Developer Q & A -- Metro Exodus dev talks Nvidia RTX: How ray tracing will speed up development and make life harder for monsters
    August 24, 2018
    https://www.rockpapershotgun.com/20...-rtx-2080-ray-tracing-metro-exodus-interview/
     
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  16. keldor

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    In most ray tracing methods, rays are traced out from the camera. The basic reason is that the distribution of pixels seen by the camera is highly skewed, favoring nearby objects. In fact, in a basic landscape scene, the distribution of the area projected to given pixels is asymptotic! This is worse than exponential! This is the "teapot in a stadium" problem.

    There are a great many ways of dealing with this, but the most simple and general solution that "just works" for a wide variety of scenes is to just shoot rays out from the camera, and bounce them toward lights to see which ones are occluded , as well as to follow reflections from shiny surfaces, calculate ambient occlusion (here we assume that there is light in all directions, and cast rays out to see how much of that is blocked by nearby objects), and so forth. Now the important metric is how many rays we can shoot out for each pixel. The more rays, the better the scene is sampled. Thus samples per pixel.
     
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  17. trinibwoy

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    With very low sample counts per pixel how do you decide which lights to test?
     
  18. OCASM

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    The brighter the light the more important it is. At least that's an optimization AMD added to the Unity GPU lightmapper (in development).
     
  19. pharma

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  20. milk

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    The current approach is, use as many of the importance sampling techniques developed by CGI in the past years, use heavy dithering and rely on spacial filtering and temporal reprojection on top of it to clean it all up.
     
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