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Reflection Falloff

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  • V Offline
    valerostudio
    last edited by 18 Jan 2012, 18:08

    Does anyone understand the FallOff settings in order to achieve this

    ReflectionBlur.jpg

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    • A Offline
      andybot
      last edited by 18 Jan 2012, 19:31

      create a new material in the vray editor "angle blend" (right click on scene materials) and pick your two colors. The start angle should be 90 and stop angle is 200 (looking at an example one I have.)

      http://charlottesvillearchitecturalrendering.com/

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      • A Offline
        andybot
        last edited by 18 Jan 2012, 19:54

        Here is a test image. The material is one I got from a car paint material, I updated it to a red material (labeled "<dark gray>") and a gray material (labeled "sw 2860 sage") (BTW, to explain the random nature of the model, I blew the roof off since the lighting was getting messed up with an interior view.)


        random test


        angle blend

        http://charlottesvillearchitecturalrendering.com/

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        • V Offline
          valerostudio
          last edited by 18 Jan 2012, 21:50

          What I am looking to do is have the reflection falloff. Like the effect you would get on a finished floor.

          cubeRender.jpg

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          • A Offline
            andybot
            last edited by 18 Jan 2012, 21:54

            Oops! You're talking about the floor material 😳
            There's a falloff texture you can use in the reflection slot.

            edit: hmm, but it would need to be in the reflection slot. Anyhow, isn't that what the fresnel effect does anyway? You could maybe play with the parallel and perpendicular color?

            http://charlottesvillearchitecturalrendering.com/

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            • O Offline
              oganocali
              last edited by 18 Jan 2012, 22:41

              Indeed fresnel map for reflective layer reduces reflection strength for more obtuse rays. The increase in fuzziness can be obtained by reducing the glossiness of the reflective layer. This is obtained with glossiness 0.85 and fresnel map with index 5. This does not fit your first case exactly (this one somehow has a smoother feel) but you may find it useful.

              good luck
              material.jpg

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              • N Offline
                nomeradona
                last edited by 19 Jan 2012, 01:47

                oganocoli was right just use fresnel refelction and blurrying it

                visit my blog: http://www.nomeradona.blogspot.com

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                • A Offline
                  andybot
                  last edited by 19 Jan 2012, 02:54

                  The first image is definitely just a blurry reflection. Like oganocali says - using .85 for glossiness would work fine. The second one has an accentuated falloff without the blurriness. I wonder if it's just a lower IOR value, like 1.2

                  http://charlottesvillearchitecturalrendering.com/

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                  • O Offline
                    oganocali
                    last edited by 19 Jan 2012, 12:16

                    I have trouble replication the graduated fall off effect in picture 2. In theory fresnel reflection should do it for small ior. Somehow vray fresnel reflection falls off too abruptly as in total internal reflection as seen (ior 1.2). I am pretty sure I have the correct surface orientation but... Apparently vray is doing some kind of approximation for this reflection. I am pretty sure the physics require a smooth graduated fall off. Strange.
                    fresnelonly.jpg

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                    • A Offline
                      andybot
                      last edited by 19 Jan 2012, 12:26

                      do you have a filter color for the reflection layer? I see that effect sometimes if the filter color is too dark. Set it at white and see if you still get that effect.

                      http://charlottesvillearchitecturalrendering.com/

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                      • T Offline
                        thomthom
                        last edited by 19 Jan 2012, 12:37

                        oganocali: remember that you also need to make the reflection blurry in order to reproduce the original image posted.

                        Thomas Thomassen — SketchUp Monkey & Coding addict
                        List of my plugins and link to the CookieWare fund

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                        • O Offline
                          oganocali
                          last edited by 19 Jan 2012, 12:51

                          @andybot: I don't have a filter.
                          @thomthom: I was trying to reproduce the effect in the 2nd picture. I feel that one does not have blurriness.

                          Well, just before the reflection drops to zero there is a small graduated region I think, may be I am imagining it.
                          There seems to be something I am missing.

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                          • V Offline
                            valerostudio
                            last edited by 19 Jan 2012, 14:11

                            Wow, I must be dense! I dont know why I didn't realize Fresnel did this. I have used it a million times. What what you use if you wanted it to fade off in a shorter distance? Would you just change the IOR value?

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                            • O Offline
                              oganocali
                              last edited by 19 Jan 2012, 14:49

                              @valerostudio: Smaller value of IOR should make the reflection fade off earlier as I understand , but somehow in vray the reflection dies off more completely and abruptly than I expect.

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                              • T Offline
                                thomthom
                                last edited by 19 Jan 2012, 15:03

                                I did use falloff once for such an effect in 3dsmax. Found it, then, easier to control in that situation than fresnel.

                                Thomas Thomassen — SketchUp Monkey & Coding addict
                                List of my plugins and link to the CookieWare fund

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                                • V Offline
                                  valerostudio
                                  last edited by 19 Jan 2012, 19:02

                                  But we all agree that fresnel is the best solution for realistic reflections? Would you ever just use a color value to control the reflection amount and not use fresnel?

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                                  • T Offline
                                    thomthom
                                    last edited by 20 Jan 2012, 09:59

                                    @valerostudio said:

                                    But we all agree that fresnel is the best solution for realistic reflections?

                                    Yes

                                    Thomas Thomassen — SketchUp Monkey & Coding addict
                                    List of my plugins and link to the CookieWare fund

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