mist anybody?

[Iancorey]

Just off the top of my head, multiple layers of tweaked Fractal noise offset in zspace set to overlay.

One thing that I’d add (if I had any clue) would be to set an expression that would make the layer less opaque the closer the camera got to it. That way there’s no “snap” to invisible as the layer ends up behind the camera.

[Filip Vandueren]

Check out the Buena Depth Cue effects,

I don’t own them but they should do the trick.

The website buena.com is no longer active, this info from toolfarm:

3D Composite – Allows 2D footage with a depth channel, such as you might generate in Maya, 3D Studio Max, or other 3D applications, to interact with After Effects’ 3D layers.

Depth – Displays the depth of each layer in grayscale for use as a gradient map with other plugins, or with other applications.

Falloff Lighting – Lights your layers realistically. Layers farther away from lights are illuminated less than those near lights.

Fog – Shrouds your layers in a light haze or a deep, murky mist. Objects farther away from the camera have more fog applied to them than objects close to the camera.

Rack Focus – Produces realistic depth of field effects and focus pulls, including simulating boke and anamorphic lens effects.

[Filip Vandueren]

Check out the Buena Depth Cue effects, I don’t own them but they should do the trick.