Fog Multiplier

[Pierreden]

I cant find any information on what i'm actually adjusting when I change this multiplier. Does anyone know?

And is it a way (a formula/calculation) so that i know that a fog material will be opaque after 10 cm "depth"?

Regards
Pierre

[dalomar_cg]

Re: Fog Multiplier

Oh, someone almost always knows what's going on . When adjusting the color of refractions, this can be done in two ways. The first is simply taking the point where the refraction begins being traced on entrance surface and generating the color of refractions based on that point. This means that this value can be mapped, but it also means that it does not take into account the thickness of the refracted volume, which is how refracted objects get their color in the real world.

Fog does use the thickness of the volume to determine the final color for the refraction. It does so by darkening and saturating the fog color. The fog multiplier simply controls how strong this affect actually is. There's something that I like to call "Fog Law" that explains exactly how Fog Color, Fog Multiplier, and refraction thickness react together.

When the refraction thickness is 1 unit thick, and the fog multiplier is 1, the color of the resulting refraction will be what is set as the fog color. As we increase the thickness of the object the resulting Fog will be darker, and thusly, as we decrease the thickness of the object the fog will become lighter. With the multiplier, a higher multiplier will darken the fog and a lower multiplier will lighten it.

Note that the appearance of Fog and its reaction to object thickness and the fog multiplier are heavily related to the Fog Color. The more saturated a given color is, the "sharper" its reaction tends to be. I've found that the most successful fog colors tend to be lighter, desaturated versions of the color that I'm looking for. In some cases (like a red wine), this will require a higher multiplier than something like glass.