What is the correct way to use zdepth passes?

[evanerichards]

I'm not certain if this is a problem inherent in using zdepth passes, or if I am doing something wrong.

I have an image I render. I take the zdepth pass and use it to compute a depth of field.

If you look in this image there is a lot of...well it sort of looks like blooming and diffusion around different objects. Look at the wires running across the top of the frame where they overlap the building to see what I am talking about.
Is this just what happens with zdepth passes? Or can I be doing something else to make it look better?

Thanks!

[csmallfield]

can you post your zdepth pass? It looks like you don't have the wires in the zdepth pass, so the depth information of the objects immediately behind them are determining the blur.

[evanerichards]

They are definitely there. Hmmmm.

[csmallfield]

the zdepth pass looks fine, what are you applying it in? Which application and what tools. If you could screen cap the comp and the settings that might help

[evanerichards]

Well in this particular case, I'm apply it in photoshop using their "lens blur" tool and then selecting the zdepth pass as the blur map.

But the results are the same regardless of what software I use. After Effects does the same thing.

[Morbid Angel]

This is because there is no pixels behind the cables to blur for. Since the zdepth is not a deep image, neither is your render, zblur does not know how to distribute those pixels. I would say you have to split the cable render and its zdepth to another layer and blur it then.