Atmospheric fog?

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Foundry Modo (Developed by stenson, Integrated Plugin developed by Paul Kinnane)

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Atmospheric fog?

Postby vantrum » Wed Jul 12, 2017 11:41 pm

vantrum Wed Jul 12, 2017 11:41 pm
I'm having trouble creating a fog element in my outdoor scenes. I've read all posts relating to a scatter node on the environment Medium - but the effect does not look like outdoor environment fog. At best, I'm able to create 'god rays' near a bright light source -- but this doesn't answer the distance fog look that I'm going for. Modern game engines are a good example of the look I'm going for: an exponential thickening of the atmosphere based on distance. The fog scatters the environment color, which is especially evident at sunrise or sunset. Currently my only technique is to use the zdepth pass in Photoshop to manipulate the color / contrast. Is there an environment setting I'm missing?

Thanks in advance for the help!
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Re: Atmospheric fog?

Postby Rahll » Sat Jul 15, 2017 12:06 am

Rahll Sat Jul 15, 2017 12:06 am
Agreed. The old trick of using a large cube or sphere that encompasses your scene provides better results still, but still isn't ideal.

The environment medium settings aren't even usable because it simply provides an overall haze with basically no falloff. Plus, it doesn't even scatter light from sources properly like doing it the old way. For example, add a point light or emissive material, set up the environment medium, and it won't scatter the light around the light source at all.

There are videos for the same setup working in C4D, and doing exactly what you'd expect, and it's really frustrating to me that we can't have accurate volumetric scene lighting in Modo after all these years.
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Re: Atmospheric fog?

Postby Rahll » Sat Jul 15, 2017 12:35 am

Rahll Sat Jul 15, 2017 12:35 am
Ah you know what, I take it back.

I played with the files in the thread below, turns out you REALLY need to play around with the Medium Radius and Density settings depending your scene. The scale makes a huge difference.

It works nicely in small scale scenes or super hazy things, but I'm still not sure how to get a nice atmospheric perspective on something like a landscape, where the blues take over the dark tones the further in the distance you look.

viewtopic.php?f=34&t=60258&p=308338&hilit=fog#p308338
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Re: Atmospheric fog?

Postby Rahll » Sat Jul 15, 2017 5:15 pm

Rahll Sat Jul 15, 2017 5:15 pm
I had set up an outdoor scene with the Octane daylight environment and got the settings tweaked really nicely where it looked pretty good as atmospheric perspective, but I got some weird errors when I tried to switch to an HDR instead of the Octane daylight and it wouldn't load the environment medium anymore.

Anyway, I'm going to try and set it up again when I get a chance later today, and I'll upload the file for people to look at. The scene files in the previous link I posted are a great start though. The settings have to be JUST right, having the wrong color, or being .5 off on a value can drastically change the output you get, it's very much scene scale dependent.

Like in those files, I found that starting with a black value in the absorption, white in the scattering, and a very low density is the way to go. Then increase medium radius in the environment settings, and playing with the density again until you get something close to what you want, and after that, messing with absorption and scattering to bring in the color you want.
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