While I think it's great to link to semideau products, in this case I don't. You can make z-depth renders directly in Poser without buying anything. It takes only 30 seconds to set up.

Turn off all your lights.
In the atmosphere material, enable depth-cue. Set the color to white.

Please do not encourage people to buy something they have already.

There are other things in his products worth getting, but if all you want is to do a z-depth render, then ...

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)