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Transparency/Trees: Vray 10X slower then Scanline??

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  • Transparency/Trees: Vray 10X slower then Scanline??

    Hello all,

    I have been testing Vray free and I like it a lot, but I noticed that it slows way down when rendering a scene with trees made with transparent planes for the leaves (game art style). When rendering this kind of scene the Scanline renderer is many times faster – So many times faster that I think I may be missing some adjustment I’m supposed to make to Vray’s settings. See images:

    http://home.san.rr.com/dionsthings/

    The test scene is very simple: One direct light plus Vray sky. The render settings are at default and I checked use GI. The shadows are simple shadow maps – no ray tracing. The trees are 150 polygons each. The materials are standard with an alpha channel for the opacity.

    Scanline = 20 seconds (for Radiosity and Rendering combined)
    Vray = 3 minutes 24 seconds

    What I would like to know is:

    1) Is this a limitation of Vray? – or do I need to adjust Vray’s settings to make the time it takes somewhat comparable to the Scanline? Not just “speed tweaks”, but something major that I’m missing to make up for this huge time difference?

    2) Do Vray Basic and Vray Advanced also slow way down when rendering these types of trees? Or do they handle transparency in a different/drastically faster way then Vray free?

    3) Is this a known issue that may/will be addressed in a future release?

    4) Does anyone know if Brazil also goes many times slower then Scanline when rendering these kinds of trees/transparent planes?

    I say again I really like Vray and I know a lot of people reading this do to, but if Transparency is its “bottle neck”, please don’t hesitate to say so. Even if it is I may purchase Vray anyway for its abilities in other areas. I’m just trying to figure out what it’s limitations are and which version would be best for my needs. Thank you much for the information!

  • #2
    Ive never used vray free, but I can tell you that it used to be horribly slow in advanced as well, until the vray mtl got an opacity map slot. I think its still slower then it should be, but remember vray is a raytracer through and through... so it raytraces everything, especially where there is less then 100% opacity.
    ____________________________________

    "Sometimes life leaves a hundred dollar bill on your dresser, and you don't realize until later that it's because it fu**ed you."

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    • #3
      It may actually be faster to set a vraymap in the refraction slot with a IOR of 1.0. and turn your opacity back to 100

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      • #4
        Originally posted by cpnichols
        It may actually be faster to set a vraymap in the refraction slot with a IOR of 1.0. and turn your opacity back to 100
        Thats what I use. The opacity slot doesnt work so well by comparason i think.

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        • #5
          VRay Free does NOT have VRayMtl and VRayMtl is the thing that handles opacity much faster than the Standard max's opacity. You can get the latest VRay Demo from our web site which has VRayMtl and test your scene again with VRayMtl - you can use the two techniques suggested above. You have to be also careful about the GI settings because the defaults are the high presets and this will slow down things additionally.
          Best Regards,
          Tisho

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          • #6
            does setting the filter type to "none" for the opacity mapped texture still help speed things up? (Im at home so cant try)

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            • #7
              actually. what i noticed was that although vray renders transparency trees slower than standard material and scanline, its when your using GI that things go faster. i havent done tests in a while however with GI turned on vraymaterial used to be 2x faster than standard material.

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