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4.15 tonemapper - is it possible to simulate old effects?

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    #16
    While I do agree with Luos that stuff looks nice with the new tonemapper, incl. Effects, I also strongly agree on the fact that its less than ideal to not be able to have a pure red surface that also has red bloom anymore. The problem with ACES is that it treats values above 1 completely different from the old tonemapper which is causing exactly those issues. I am not too sure though if those could be fixed fairly easily :S Although, I would like to see something similar to the ACES tonemapper that still handles those cases a lot better!

    Cheers!
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      #17
      Originally posted by Luos View Post


      not sure whats going on with ssr.
      But that aint right.
      SSR might be reflecting the diffuse values excluding emissive, thats why you see this difference in value?
      Last edited by Daedalus51; 02-18-2017, 10:42 AM. Reason: rephrased the sentence since I am not exactly sure whats happening^^
      Check out UNREAL 4 Lighting Academy
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        #18
        Originally posted by Daedalus51 View Post
        While I do agree with Luos that stuff looks nice with the new tonemapper, incl. Effects, I also strongly agree on the fact that its less than ideal to not be able to have a pure red surface that also has red bloom anymore. The problem with ACES is that it treats values above 1 completely different from the old tonemapper which is causing exactly those issues. I am not too sure though if those could be fixed fairly easily :S Although, I would like to see something similar to the ACES tonemapper that still handles those cases a lot better!

        Cheers!
        which is why I suggested to have an additional input for materials that just adds glow, instead of emissive.
        though, this might sound more proper in my puny brain than it actually is.

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          #19
          Originally posted by Daedalus51 View Post
          SSR is reflecting the diffuse values excluding emissive, thats why you see this difference in value.
          Based on what?
          Reflection are handled in linear space before tonemapping. Floor isn't perfect mirror so it's does not reflect 100% so it's make reflection dimmer. With new tonemapper those bright blue pixels are shifting towards white but reflected blue isn't that bright so you don't see the shift.

          Same is happening at this photo for cloud orange tint. Cloud look lot less orangy than it's reflection from lake. http://visitrainier.com/wp-content/u...dd-700x400.jpg

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            #20
            Originally posted by Kalle_H View Post
            Based on what?
            Reflection are handled in linear space before tonemapping. Floor isn't perfect mirror so it's does not reflect 100% so it's make reflection dimmer. With new tonemapper those bright blue pixels are shifting towards white but reflected blue isn't that bright so you don't see the shift.

            Same is happening at this photo for cloud orange tint. Cloud look lot less orangy than it's reflection from lake. http://visitrainier.com/wp-content/u...dd-700x400.jpg
            Well, its just a guess. Also...your example looks heavily Photoshopped so I would not take it as a reference. Besides that, the energy loss caused by diffusion/microfacets should not be that extreme since the floor is still very close to a mirror reflector.
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              #21
              I think it would, since it's a very dark floor despite its perfect reflectivity.

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                #22
                Incidence of reflections are completely different in those two examples - the lake is at grazing angles so the reflection value is close to 100% whereas the particles on the tiles is getting towards 0 degrees (to the eye ray) and so would be closer to 4% = major difference. Remember a tiled floor is a dielectric and a mirror is backed by a layer of metal which is a conductor and so can reflect at 0 degrees at almost 100%.

                Your example looks physically correct to me - but perhaps you just want something stylized which is fine.

                I've got another thread going on HDR - but this new behaviour is critical to having HDR display correctly and not look bizarre that there's a 'bright' colour causing bloom which in HDR is actually barely bright and then a particle system next to it throwing sparks with correct Black Body levels is scorching hot then the skybox behind everything is flat and dull because it's a low dynamic range jpeg.

                Of course i'm only talking about photo-realistic rendering. Unreal makes some great cartoon/stylized stuff so there needs to be modal behaviour to support every avenue.

                Matt Hermans

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                  #23
                  Your example looks physically correct to me
                  |

                  wouldn't the U from the unreal logo and all the words not behave the same way then and turn more blue-ish?


                  additionally
                  Many of us with untrained eyes are claiming this looks wrong, regardless if it is in fact physically correct.
                  And if we do, you can bet that any average person who is playing the game/project/showcase, and any client/boss might also claim it looks wrong.
                  In those cases (especially if a client demands it) we need to be able to change it on the fly.
                  Last edited by Luos; 02-19-2017, 06:22 AM.

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                    #24
                    I think the color values need to be pushed beyond 1

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                      #25
                      Ultimately there's no way to keep colors from tending towards white with the tonemapper. That seems to be what it's for, more than anything else. By which I mean to say that it's not exclusively for HDR displays, or possibly even essential for them.

                      What is strange is that green tends towards white as you'd expect, but blue tends too much towards purple, and red tends too much towards orange. You can add a little more green to your blues and a little more blue to your reds and it will look much better. Could be an error with the Linear color>>ACES conversion.

                      Originally posted by Renbry View Post
                      I've got another thread going on HDR - but this new behaviour is critical to having HDR display correctly and not look bizarre that there's a 'bright' colour causing bloom which in HDR is actually barely bright and then a particle system next to it throwing sparks with correct Black Body levels is scorching hot then the skybox behind everything is flat and dull because it's a low dynamic range jpeg.
                      If a colour is causing bloom, it's already bright. It won't look flat and dull compared to sparks because they're relying on the same data for brightness. If anything, SDR is underrepresenting just how bright these things should appear. E.g. That mushroom in the OP would look as bright as the sun in HDR. After ACES, the only change its that it's now white instead of orange.
                      Last edited by Dementiurge; 02-19-2017, 08:21 PM.

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                        #26
                        Hi Luos -

                        A surface can only reflect something in a different colour than the source if it's a conductor (Metallic e.g Gold) That tiled floor is a dielectric which is why the more grazing reflections are 1:1 with their source (the background details) The 'strangeness' of the particles is because the source is a fairly bright blue but is being tone-mapped into the colour you see but the lower reflection levels show a darker colour blue which is correct.

                        I totally get what you're saying but in the VFX world we've only been in this PBR-style land for less than a decade so we're used to having reliable surface responses to light. Realtime engines are just here now so we're in a transition zone of confusion and frustration.

                        Here's a great example - in standard dynamic range the brightest value can only be WHITE (255,255,255) so to make a bright RED we have to do strange things like enable BLOOM to pretend it's brighter. With an HDR display you could make that red very bright and the display would show a very bright RED (e.g neon) and you wouldn't need to use any blooming what so ever.

                        Attaching a picture I put together - the pixel values of the brights on the left side are all WHITE (there is lighting bleed onto the surrounding surfaces which gives you the idea there is actually colour involved) but the right side is stopped down to see the real colours of the lights. Since 4.15 we're able to work with these sorts of correct colour intensities and have them mapped back down into our SDR display range. An HDR display would be more capable of showing those colours on the right however and this is what i'm personally working towards so that when desktop and VR displays are HDR capable then all my assets/work is ready for their enhanced abilities.

                        The Tonemapper should be able to be tweaked for SDR display and not cook so white - I haven't had a chance to get under the hood - but that picture is from another experiment i'm working on (high dynamic range photogrammetry) so I'll see what I can find.

                        Matt Hermans

                        Click image for larger version

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                          #27
                          Besides the tone mapper, I want my specular color controls back from UDK ! Hope they add something in with the new stuff so that we can control the colors !

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                            #28
                            Originally posted by Renbry View Post
                            Hi Luos -

                            A surface can only reflect something in a different colour than the source if it's a conductor (Metallic e.g Gold) That tiled floor is a dielectric which is why the more grazing reflections are 1:1 with their source (the background details) The 'strangeness' of the particles is because the source is a fairly bright blue but is being tone-mapped into the colour you see but the lower reflection levels show a darker colour blue which is correct.

                            I totally get what you're saying but in the VFX world we've only been in this PBR-style land for less than a decade so we're used to having reliable surface responses to light. Realtime engines are just here now so we're in a transition zone of confusion and frustration.

                            Here's a great example - in standard dynamic range the brightest value can only be WHITE (255,255,255) so to make a bright RED we have to do strange things like enable BLOOM to pretend it's brighter. With an HDR display you could make that red very bright and the display would show a very bright RED (e.g neon) and you wouldn't need to use any blooming what so ever.

                            Attaching a picture I put together - the pixel values of the brights on the left side are all WHITE (there is lighting bleed onto the surrounding surfaces which gives you the idea there is actually colour involved) but the right side is stopped down to see the real colours of the lights. Since 4.15 we're able to work with these sorts of correct colour intensities and have them mapped back down into our SDR display range. An HDR display would be more capable of showing those colours on the right however and this is what i'm personally working towards so that when desktop and VR displays are HDR capable then all my assets/work is ready for their enhanced abilities.

                            The Tonemapper should be able to be tweaked for SDR display and not cook so white - I haven't had a chance to get under the hood - but that picture is from another experiment i'm working on (high dynamic range photogrammetry) so I'll see what I can find.

                            Matt Hermans

                            [ATTACH=CONFIG]130060[/ATTACH]
                            Hey Matt,

                            thanks a lot for further explaining the tonemappers behavior! Great to see some better visualizations!

                            I have to say though that the reflections still look wrong from SSR as I have some kind of "proof" since we are also rendering for HDR and our SSR reflect exactly what you see on screen. So I am really confused.
                            Also, in your image, you can see how the properly exposed reflections of the cars headlights look. They look strong and match the exposure of the image.

                            The example with the blue effect from unreal looks like if we would take the reflections from you right image and put them into the left one. And that just feels wrong.
                            I think it would be really awesome if someone from Epic would comment on this so we can get an understanding of whats going on under the hood

                            Thanks again and cheers!

                            EDIT: I actually remember now that we had a similar problem with emissive surfaces and reflections but it wasnt on the SSR where values were wrong, it was in the reflection volumes. It had something to do with the buffers where emissive information was stored and the reflection captures didnt have proper access to that information. So maybe something similar is wrong here? But yeah....different engines=different problems
                            Last edited by Daedalus51; 02-20-2017, 07:17 AM.
                            Check out UNREAL 4 Lighting Academy
                            https://forums.unrealengine.com/show...ng-like-that-)

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                              #29
                              It's easy to look SSR code. It's just take previous frame linear color(before tonemapping) and use that with proper specular BRDF. In above screenshots you can see clearly how reflection of billboard is looking greenish but the billboard is white. In right picture reflection is hard to even see because street isn't perfect mirror.

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                                #30
                                Please forgive a noob his noobification...

                                Surely, there is a difference between:-

                                1) Materials
                                2) Rendering
                                3) Post-processing

                                IF, the materials being created are part of a PBR/Linear workflow then (pre-runtime) we are rendering levels/maps to fit into a Post-Production 'world', where the environment artist(s) decide what filter to put on the lens the player is looking through?

                                Simply, this is a run-time issue and not a pre-runtime issue.

                                UE4 is a PBR system - should we not be focusing on making the initial pre-runtime rendering as awesome as possible, like pushing color values and dynamic ranges are far as the laws of physics allow?

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