Fog noise and fog colour connection is strange

[stevesideas]

If I set up a basic vrayenvfog effect with 1000 units high and 10000 units distance and render, the noise is very noticeable. Even if I boost the subd's for the fog and make sure the color mapping values etc are all good.

If however I put a gradient ramp into the colour slot of the vrayenvfog the noise pretty much disappears. This seems like strange behavior to me.

[cheerioboy]

Nice find. I'm working with a bit of fog at the moment and tried using a gradient ramp for the color, matching the same color I was using across the ramp. I feel like whatever it's doing, it's also taking longer to process. So it doesn't seem like a magic fix to the noise. But this solves my noise issue

[vlado]

When you add a texture, the environment fog switches its sampling method to raymarching and instead of random samples in the fog, uses the "step size" parameter to step through the volume and evaluate the textures.

Best regards,
Vlado