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    realtime global illumination - what is the current most used best way?

    Hi there!
    I just was reading the docs about realtime global illumination and searched through google and forum about various techniques, but I am stil confused now.

    So what is currently the best way to add realtime GI to a scene? Is that still 'light prop. volume'? Which one has to enable first through the INI file? (sounds like it is not really recommand to use it)
    Are there any other techniques?

    best regards T

    ps: i am not looking for the baking version, I really would love to see the realtime version.

    #2
    There is no current best way cause there is only 1 option, which is 2000 year old LPV's. Rumors have it even the Egyptians used it when creating the grande Pyramids.
    Yes you need to enable it via .ini because it's so deprecated, Epic never dared enabling it by default.
    There's also VXGI by NVIDIA which is newer but more expensive and requires a separate version of the engine.
    This probably didn't help at all.

    If you want a better answer, search around a bit.
    There's many many topics with extensive discussions and useful stuff on your question.
    Last edited by Chesire; 05-04-2016, 05:04 PM.
    https://www.artstation.com/chesire

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      #3
      Well real time global illumination is voodoo magic where you mix a combination of different ingredients to bake a result using a post process volume.

      Real time as in jump the uncanny valley real will not happen until we have real time ray trace.
      Clarke's third law: Any sufficiently advanced technology is indistinguishable from magic.
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        #4
        Originally posted by Millionviews View Post
        Hi there!
        I just was reading the docs about realtime global illumination and searched through google and forum about various techniques, but I am stil confused now.

        So what is currently the best way to add realtime GI to a scene? Is that still 'light prop. volume'? Which one has to enable first through the INI file? (sounds like it is not really recommand to use it)
        Are there any other techniques?

        best regards T

        ps: i am not looking for the baking version, I really would love to see the realtime version.
        The only official solutions are LPV, which is what you mentioned, DFGI (Distance Field Global Illumination, a GI solution piggy-backing on DFAO), HFGI (Heightfield Global Illumination, similar to DFGI but is intended for landscapes as landscapes don't produce a distance field representation of themselves), Lightmass GI (baked global illumination, can be done through static or stationary lights), or VXGI in the GameWorks branch.

        Lightmass GI is the cheapest and arguably the best looking, but it's static, VXGI is the best dynamic solution but is expensive, DFGI and HFGI are both pretty good WIP solutions and LPV is about the cheapest and lowest quality solution.

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          #5
          Originally posted by jcm2606 View Post
          VXGI is the best dynamic solution but is expensive
          How much will Pascal lessen that expense... Any guesses?

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            #6
            Originally posted by franktech View Post
            How much will Pascal lessen that expense... Any guesses?
            Depends (on a lot). I can almost 100% guarantee you the early estimates of 10x Titan-X performance won't fly though
            https://www.artstation.com/chesire

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              #7
              Originally posted by franktech View Post
              How much will Pascal lessen that expense... Any guesses?
              As Chesire pointed out, really depends on the context. Logically, I'd imagine that the cost of VXGI increases as scene complexity increases, due to voxelisation being more complicated to solve. Pascal may improve performance, but I'd imagine VXGI would still remain a feature primarily for high-end cards.

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                #8
                There is also AHR
                Never say Never, Because Never comes too soon. - ryan20fun

                Frames Per Second is NOT a proper performance metric, You should use frame time. You can read this or this as to why.
                (Profiling) Tools: RenderDoc (UE4 Plugin), NVIDIA nSight, AMD GPU PerfStudio, CodeXL
                Good articles/Series: A trip through the Graphics Pipeline 2011

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                  #9
                  Originally posted by ryan20fun View Post
                  There is also AHR
                  Forgot about AHR, though you do need to use Ryan's own branch.

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                    #10
                    Originally posted by jcm2606 View Post
                    Forgot about AHR, though you do need to use Ryan's own branch.
                    And you need VS2015 with C++ to compile it too.
                    And about ~40GiB's free space for intermediate files.
                    Never say Never, Because Never comes too soon. - ryan20fun

                    Frames Per Second is NOT a proper performance metric, You should use frame time. You can read this or this as to why.
                    (Profiling) Tools: RenderDoc (UE4 Plugin), NVIDIA nSight, AMD GPU PerfStudio, CodeXL
                    Good articles/Series: A trip through the Graphics Pipeline 2011

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                      #11
                      I can't really comment on exactly when VXGI (which to me seems like the most promising realtime GI-solution available atm) will be viable to use, but I think it'll be 1-2 more graphics cards generations until you can use it freely in big scenes, since it's quite a resource hog. My (admittely very limited) tests show that my framerate (Titan X with a i7-5720 CPU and 48Gb memory) drops by about 40 fps when enabling VXGI. My tests were done on UE4.10, and some things might have changed since then.

                      I would think that VXGI would run smoothly on the next generation of Titan, but that's a very expensive card, so you'd probably have to wait one more generation in order to use it on midrange hardware.
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                      Architectural and product visualisations

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                        #12
                        With VXGI (and just about any scalable Real-Time option I reckon) it matters a lot ofc. what you need it for. If you are content with LPV-ish quality, it can handle that with ease on mid-range GPU's already. If you want it to just render pretty images/sequences, you could upscale just for that part while having lower quality in-editor. Thing with these type of advices is they don't mean much. Yes hardware will always become better but so will pipeline demands. In one or two generations it will indeed be true that for current stuff it will be faster, just as it will most likely be true that it will be equally slow for what's considered Next-Gen by then.
                        https://www.artstation.com/chesire

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                          #13
                          Check out Enlighten

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                            #14
                            Originally posted by HuntaKiller View Post
                            Check out Enlighten
                            Enlighten requires baking and other work too. It's not fully dynamic.

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                              #15
                              Isn't Enlighten in UE4 intended for rich kids anyways?
                              https://www.artstation.com/chesire

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