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    light propagation

    Hi,

    After rendering, when in game mode with eye adaptation activated, I usually get light propagation problems on modular walls and other related meshes (properly uv'd) located in dark areas :

    What would be the best way to deal with this issue ?

    - increase the lpv bias mutlplier of those objets ?
    - make a bigger mesh (less modular elements) ?
    - add light importance volume in dark places ?
    * increase the lightmap of those objects (it's a thing I'd like to avoid to keep render times reasonnable)

    Thanks a lot for any help !

    #2
    any idea ?

    Comment


      #3
      Are you using light propagation volumes? That feature would be completely dynamic and not use any baked lighting

      The issue I'm seeing there is usually due to modular assets with baked lighting, each item will be processed individually and settings like lightmap smoothing can make them not match up together. While there's ways to reduce the problem, it is better to control how you're using modular assets so that you aren't using so many of them, that part should be one mesh rather than 6+. It will fix the lighting issue and it will improve performance since it will lower the draw calls. Anything that should be one surface will have that issue with the lighting if you build it out of multiple objects.

      Comment


        #4
        Hi Darthviper107.

        Thanks for the advices.

        No I do not use LPV. The project director insisted that we must use baked lighting rather than dynamic for this is a VR project. Do you think it would be better to use dynamic lighting for our VR demo ?

        The problem is truly due to the modular assets. But I thought, after reading so everywhere that it was better to use many modular assets rather than a big one (width of a modular here is 2 meters, so if i make a single asset, it will be 12m long. I do agree with you though that using a single mesh here would solve the problem (rather than playing with ressource greddy lightmap size and bounces) and that's what I am currently doing back in my modelling software

        If I understand well, for walls 100m long and for all the same kinds of assets that are supposed to look like a continuous surface, I should use one mesh rather than multiple assets ?
        Last edited by Trucabulles; 10-13-2019, 12:57 PM.

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          #5
          I´m not a professional like most people that will reply you around here but If your project is VR focused and you need those assets to cast dynamic shadows for instance, I would probably just turn them into distance mesh fields and see if the issue persists. I´ve had a similar issue and turning the mesh I had issues with as a distance field mesh fixed the problem for me.

          Comment


            #6
            Thanks Mac3d, I'll give this a try too.

            Comment


              #7
              Dynamic lighting will look worse and run worse. The main limitation of making larger objects to represent complete surfaces is that for large surfaces you might not be able to get enough detail in the lightmap even at a high resolution, however those cases are very rare and depend on what you're making.

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                #8
                Thanks. Would you mind developing about what you wrote previously (there's ways to reduce the problem) for my complete information ?

                Comment


                  #9
                  Originally posted by darthviper107 View Post
                  Are you using light propagation volumes? That feature would be completely dynamic and not use any baked lighting

                  The issue I'm seeing there is usually due to modular assets with baked lighting, each item will be processed individually and settings like lightmap smoothing can make them not match up together. While there are ways to reduce the problem, it is better to control how you're using modular assets so that you aren't using so many of them, that part should be one mesh rather than 6+. It will fix the lighting issue and it will improve performance since it will lower the draw calls. Anything that should be one surface will have that issue with the lighting if you build it out of multiple objects.
                  LPVs according to docs, are, " Light Propagation Volumes are a feature in development and not ready for production.", and true they aren't part of volumes to be added to scenes, BUT they are there under 'add new' , under Blendables > LPV Blendable.

                  Is this the expected use, just wondering as the doc page notes to use post-process, but post-process has ONE field, named light bias. Is this a moving target, should it be used at all yet? Seems so as opening LPV blendable DOES open up what is seen here: https://forums.unrealengine.com/comm...agation-volume , but that's old, and finding this, " Didn't LPV get abandoned in a broken/unfinished state because Lionheart Studios (the people who were actually developing it) tanked? The last thing I heard (gossip and speculation) is that Epic was not gonna finish it because they're focused on RTX now", from https://www.youtube.com/watch?v=t9MbdgJkq9M , while hardly conclusive, I'm wondering if it's worth bothering with?

                  Thx
                  Last edited by neighborlee; 10-17-2019, 02:43 PM.
                  Solo but Seismic - feel free to apply
                  https://neighborlee1.wixsite.com/theheartseed

                  Comment


                    #10
                    Originally posted by neighborlee View Post

                    LPVs according to docs, are, " Light Propagation Volumes are a feature in development and not ready for production.", and true they aren't part of volumes to be added to scenes, BUT they are there under 'add new' , under Blendables > LPV Blendable.

                    Is this the expected use, just wondering as the doc page notes to use post-process, but post-process has ONE field, named light bias. Is this a moving target, should it be used at all yet? Seems so as opening LPV blendable DOES open up what is seen here: https://forums.unrealengine.com/comm...agation-volume , but that's old, and finding this, " Didn't LPV get abandoned in a broken/unfinished state because Lionheart Studios (the people who were actually developing it) tanked? The last thing I heard (gossip and speculation) is that Epic was not gonna finish it because they're focused on RTX now", from https://www.youtube.com/watch?v=t9MbdgJkq9M , while hardly conclusive, I'm wondering if it's worth bothering with?

                    Thx
                    Don't use LPV, it's not developed enough and it's not getting any attention

                    Comment


                      #11
                      K thx darth !
                      Solo but Seismic - feel free to apply
                      https://neighborlee1.wixsite.com/theheartseed

                      Comment

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