exclude Volumetrics from the Depth Pass (Z-Buffer)

Cycles currently includes volumes into the depth channel calculations, which results in totally unusable noisy depth passes. Look at this Depth pass of my current project for example (it’s the stuff of nightmares):

That bright wall of noise which starts behind the trees is what happens when you use a simple cube with a volume shader to add some subtle fog to your scene. The actual beauty render looks like this:

The scene extends far beyond the wall of noise which is rendered in the depth channel since there starts the volume

It would be great to have an option that allows you to exclude volume from the calculation of the depth pass and other auxiliary passes, such as “Position”

The current workaround is, to create an additional render layer where you disable just the volume and render just the depth channel . But this increases the render time a lot since the scene has to be renderd more or less twice just to get a usable depth channel .

Besides that it would be really much needed to have an antialiased depth pass which also takes into account opacity mask (e.g. on leafes) to add proper depth fog in compositing