The Fog 3D effect simulates fog by behaving as though there is a scattering medium in the air that makes objects look more diffuse as they get more distant along the z axis.

This effect works with 8-bpc color.

Original (top left), Gradient Layer (bottom left), and with Fog 3D applied (bottom right)

Fog Start Depth

Where along the z axis the diffuse scattering begins.

To determine the depth of an object, click it in the Composition panel or Layer panel using the Selection tool while the effect is selected.

Fog End Depth

Where along the z axis the diffusion reaches its maximum.

Scattering Density

Determines how quickly the scattering occurs. The higher the value, the more dense the fog appears from its starting point.

Foggy Background

Creates a foggy background (default). Deselect to create transparency at the back of the 3D scene for compositing on top of another layer.

Gradient Layer

(Optional) A grayscale layer to use as a control layer, the luminance values of which apply to fog density. For example, use the Fractal Noise effect to create a swirling control layer for atmospheric fog. Make sure that the dimensions of the gradient layer are at least as great as the dimensions of the 3D scene layer.

Layer Contribution

How much the gradient layer affects the fog density.