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    Regarding Exponential Height Fog itself regardless of Volumetric Fog being enabled:

    One thing I don't understand is that why Exponential Height Fog is already lit by itself while there is no Directional or Skylight placed in the level?
    A realistic approach would be for the fog to be lit by Directional and Skylight. It's brightness should be bound to Directional and Skylight intensity, and it's color should be bound to skylight color. That's a very simple, yet very nice step towards having a more physically based fog. Artists will be able to achieve more realistic results. (While having overrides for brightness and color for artists to be able to achieve stylized settings as well).

    What do you think about that?
    Last edited by Maximum-Dev; 05-29-2017, 06:24 PM.

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      Originally posted by Maximum-Dev View Post
      Regarding Exponential Height Fog itself regardless of Volumetric Fog being enabled:

      One thing I don't understand is that why Exponential Height Fog is already lit by itself while there is no Directional or Skylight placed in the level?
      A realistic approach would be for the fog to be lit by Directional and Skylight. It's brightness should be bound to Directional and Skylight intensity, and it's color should be bound to skylight color. That's a very simple, yet very nice step towards having a more physically based fog. Artists will be able to achieve more realistic results. (While having overrides for brightness and color for artists to be able to achieve stylized settings as well).

      What do you think about that?
      +1 That would be more natural & flexible, imho.

      Comment


        Originally posted by Maximum-Dev View Post
        Regarding Exponential Height Fog itself regardless of Volumetric Fog being enabled:

        One thing I don't understand is that why Exponential Height Fog is already lit by itself while there is no Directional or Skylight placed in the level?
        A realistic approach would be for the fog to be lit by Directional and Skylight. It's brightness should be bound to Directional and Skylight intensity, and it's color should be bound to skylight color. That's a very simple, yet very nice step towards having a more physically based fog. Artists will be able to achieve more realistic results. (While having overrides for brightness and color for artists to be able to achieve stylized settings as well).

        What do you think about that?
        Exp fog isn't even PBR, so I'm not sure that would do much. It would just be skylight * directional * fogcolor * densityatpixel, instead of fogcolor * densityatpixel. You could do the multiplication yourself. Edit: I'm easily distracted by my own misconceptions. What I mean to say is, it would be great to have some PBR "love" given to exp fog. I'm not sure if basic light interaction in particular would be especially useful, since exp fog doesn't benefit from occlusion like vol fog does, but there are likely other ways to take advantage of it without going all the way towards vol fog's expensive implementation, and it would be fun to brainstorm such ideas.

        I suppose I should ask, how just how closely knit is vol fog to exp fog? They seem like completely independent features that are just tied to the same actor for convenience.
        Last edited by Dementiurge; 05-29-2017, 10:04 PM.

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          Hey everyone,

          Loving 4.16! Though I'm having some weird shimmer/glitter show up and i'm not 100% sure why this is happening.

          Click image for larger version

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          Anyone had the same problem? If so does anyone know how to get rid of it?

          Cheers!

          Comment


            Could it be related to all those point lights?

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              Set the points lights volumetric scattering to 0.

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                Awesome! That worked perfectly, cheers dude!

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                  Originally posted by Maximum-Dev View Post
                  Regarding Exponential Height Fog itself regardless of Volumetric Fog being enabled:

                  One thing I don't understand is that why Exponential Height Fog is already lit by itself while there is no Directional or Skylight placed in the level?
                  A realistic approach would be for the fog to be lit by Directional and Skylight. It's brightness should be bound to Directional and Skylight intensity, and it's color should be bound to skylight color. That's a very simple, yet very nice step towards having a more physically based fog. Artists will be able to achieve more realistic results. (While having overrides for brightness and color for artists to be able to achieve stylized settings as well).

                  What do you think about that?
                  That would be nice feature to have but it should be optional. Indoors levels would still be a problem because there are no sky or directional light.

                  Comment


                    How do you do the noise he talks about but doesn't show? im just getting bubbling white cloudy spheres. What should the particle size be?

                    Comment


                      Is this feature for the deferred renderer only? I got it working with deferred, but not with forward shading turned on.

                      Comment


                        Finally giving this a try.

                        The way Volumetric Height Fog works is that you don't see the fog in shadowed parts. However, when placing vol fog as a particle sphere, you still get to see the fog in the shadowed parts too and that's not how it works in real life. Am I missing something?



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                          Originally posted by Maximum-Dev View Post
                          Finally giving this a try.

                          The way Volumetric Height Fog works is that you don't see the fog in shadowed parts. However, when placing vol fog as a particle sphere, you still get to see the fog in the shadowed parts too and that's not how it works in real life. Am I missing something?
                          Your light isn't bright enough and your fog is much too dense. Here's some reference for light shafts in caves:

                          https://headfirstadventuresdotcom.fi...light-beam.jpg

                          http://richardbarron.net/traveller/w...-canyon-02.jpg

                          Notice how the pools of direct light are blown out. The light source is bright enough that even a tiny amount of fog (like you'd expect to see in a cave) can create visible shafts.

                          Here's something made in unreal:
                          Click image for larger version

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                          The Volumetric scattering intensity is at its default value of 1.0, and the exponential height fog density is 0.5

                          If you want even thinner fog, you can use particles to model where airborne particles should appear. If you create a particle system which spawns at the ceiling crack and drifts down (simulating sand/dust/pollen from outside) you can eliminate the fog entirely.

                          Exposure and light intensity should have the same effect. If you light value can't change for whatever reason, just increase your EV and try to match reference.

                          Comment


                            [MENTION=22762]mbullister[/MENTION]. Perhaps I wasn't clear.

                            Using the exponential height fog it works fine. But my issue is with particles. I've already placed a particle entity inside the cave and the problem is that I continue to see fog in the shadowed parts.




                            Expected behavior would be to see the fog only in the lit area (below the crack only). However, as you can see here I'm seeing dense fog everywhere in the shadows as well. Fog shadows seem to be not working properly with particles.

                            Comment


                              Did anyone figure out how to subtract from the fog?

                              Comment


                                Does anyone know if there's a way to maintain fog density on small particles? I was setting up a rolling fog particle similar to RyanB's one from his Shaderbits blog (link). He mentions that a small, camera-linked sprite would be better for performance than a gigantic one encompassing the entire level. However, from all of my experiments, it seems that the density of the fog is directly affected by the size of the particle, even when it's not sampling the particle radius. Here's the bit I'm specifically trying to deal with from his blog post:
                                The cost of using a pseudo volume scales with size of the particle and tiling of the texture. The more heavily tiled the coordinates are, the more expensive. This is made worse by the fact that the VolumeTextureFunction as released currently forces MipLevel which prevents mips from reducing the cost. I will have a fix for that soon, but for now you can use derivative mode and hook up the XY coords. Using default derivatives with the volume fog just breaks the effect.

                                Try to keep any 'whole screen' particles from being larger than necessary. It may even be beneficial to use blueprint script to move them with the camera instead of making them larger.
                                But shrinking the particle size down to something that would fit just in front of the camera (or even roughly human scale at around 200uu) caused the system to fade out and lose all the interesting density. To make sure I wasn't doing something screwy, I ran a test with an extremely simple fog particle material with an albedo of 1 and extinction of 0.5, attached it to my camera, and then simply scaled the particle up and down. What I confirmed is that even if the particle covers the entire camera frustum, the apparent density of the effect as it recedes into the distance is directly linked to the scale of the particle (set in either Cascade through the size node or in the editor through simple scaling of the particle system - scaling either responds identically). See the shot of the material below - I'm specifically not using the ParticleRadius node to influence the density, theoretically this material should be showing the same fog density so long as the camera is looking through it.

                                This basically prohibits the notion of creating a tiny camera-linked particle system that fakes the effect of a much larger (and less performant) one. I'm not sure if this is a bug, a limitation with the current implementation of Unreal's volumetrics tech, or something that can be remedied in some way. Here are the shots detailing my experiments trying to isolate the issue:







                                And here's the particle system with the particle size of 1024 for it's default 1.0 scale (ideally this would only be anywhere from 64 to 256uu in size if sitting just in front of the camera):


                                ---------------------------------------------------------------

                                EDIT: Unrelated to above, but I'm super happy to hear the moveable light reflection capture issue sounds like it's being addressed!
                                Originally posted by Maximum-Dev View Post
                                As Tim says, only when your light is Stationary and is baked the reflection capture picks it up. Which is odd.
                                I can see why Movable lights aren't captured. Because if they are captured and then the light moves, the reflection capture won't update. But that's where you can let the artist to decide which lights shouldn't be captured since not everyone bakes lighting and not every movable light is going to be moved.
                                +1 Same deal with the project I'm working on.

                                Originally posted by DanielW View Post
                                I can see how this is a problem when you might want to use Movable to get better quality. Or maybe you do move the light, but you prefer the reflection captures to capture it anyway. I think the default is good (exclude them) but I'm going to add an override so that if you have a movable light you want in a reflection capture, you can force it in there.
                                Thank goodness! This will be a lot cleaner than having to constantly drop in cube capture actors, capture, save out those captures, then manually plug them into reflection actors, and then do it all over again every time we update anything just because our lights are moveable.
                                Last edited by Nick!; 08-22-2017, 07:50 PM.

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