Exclude one object from writing any values to the Z depth buffer?

I may have overlooked something, so please excuse if this is something simple.

I have a scene with a lot of objects, I also have them on multiple scenes and composited with a particular node set up.

There is just one object interfering with the Z Combine node and I know exactly what the problem is. But I don’t know how to fix it, I just need that one object to NOT write itself to the Z buffer but allow all the other objects to write to the Z buffer as they normally do (and yes they all have to be in one layer unfortunately).

Is there a way to do that?

I’m having the same issue. I started experimenting with using Z-Depth to help create a mist type effect in a scene. The scene I am working with however contains a few smoke simulations. Z Depth is treating the entire domain as an object, and so I’m ending up with a bunch of domain shaped cutouts in my mist. Is there a way to exclude domains from the Z Depth?

You might try creating a second renderlayer just for the purpose of obtaining the Z-depth, so you still have your main image the way you need it while having the depth information you want.

Thanks, I’ll give that a go.

So the layers idea worked great, but is it possible to exclude my world texture from the z depth as well? I’m trying to create mist/haze in Blender Internal and would like the sky excluded.

You can choose to exclude the world texture during the render itself and add it back in through compositing (enable the environmental pass checkbox and disable its visibility in the combined pass (the little camera icon).