01 January 2008, 09:12 PM
Here's the deal. I'm creating an ocean scene from an airplane with two fluid effects containers. One for the horizon fog, and one for the clouds. They both look great seperately, but when rendered together they don't look so hot. I increased the volume samples and that reduced the noise at the horizon, but created another problem with the alpha channel that causes them to be composited funky. I've attached images of the various renders so you can see what's going on more clearly. The first image is the ocean and sky. The second image is the ocean, sky and horizon fog. The third image is the ocean, sky and clouds. The fourth image is all three together, and the fith image is all three with volume samples turned up.
With the volume samples up the noise goes away, but the horizon fog is really dark on top of the sky. When you look at the alpha images you can see the difference that makes it not comp right. In the final two images the color channel is almost identical, it's just the alpha that is different.