• tamte 2 years, 1 month ago  | 

    never use uniform volume on an actual volume geometry
    for the best results keep box as a polygonal geometry and apply uniform volume shader
    - it will be independent of volume quality sliders
    - so just adjust Volume Samples on material and Stochastic samples on Mantra to get fast and clean godrays, no need to crank up pixel samples

    • malbrecht 2 years, 1 month ago  | 

      Hi, @tamte,

      thanks for the additional info! I will publish an update to the quicktip ASAP.
      In my experiments I found the outcome of a "volume-shader-only" render much less convincing (may I say "realistic"?) than with a volume added to the geometry. Admittedly, a volume shader on a volumetric item probably is overkill and maybe a "no go" (as you say "never use ..."), alas when experimenting with the settings, I found this to give you the most flexibility to get the look that you want.

      But anyway, omitting the convert-to-fog definitely gives you "cleaner" results in the same time, so, again, thanks!

  • MarcelPP 5 months, 3 weeks ago  | 

    Hi tamte and malbrecht,

    thank you very much for this video. The fog volume try works for me. The "update" trick does not. I use Houdini 16.5 (can't use 17 for other reasons)

    Question: when using the fog volume my image get darker the bigger I make the initial box. This is the only thing preventing me from using this. Do you experience the same? I have an environmental map and light so maybe these tricks don't go well together?



    • malbrecht 5 months, 3 weeks ago  | 

      Hi, Marcel,

      without knowing your scene setup, my assumption would be that a bigger fog volume is "eating up" more light, which makes physical sense. You cannot compare a computer scenario with real life: In real life, a FOG always gets enough photons from the sun to evenly distribute light, so it doesn't "feel" darker. But in a computer environment, your number of photons is limited - and if they get scattered through the fog volume, fewer will hit your "camera".
      Depending on your renderer (I don't know Mantra very well, in fact I know nothing very well) you may have the option to increase the number of photons .

      Marc (without the "-el", which, according to Tolkien, stands for "kingly origin")

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