Creating A Depth Map Using The Atmosphere 'Depth_Cue' (shorter version of the post! :)
( Doing DoF inside Poser already covered - http://www.renderosity.com/mod/forumpro/?thread_id=2888795&#msg4193643 )
- The usual 'turn off the lights' approach:
http://www.renderosity.com/mod/forumpro/?thread_id=2821053#msg3760022
http://forum.runtimedna.com/showthread.php?26700-Depth-Map
- turn of all lights
- activate "DepthCue_On" (Atmosphere material)
- set DepthCue_Color to white
- set DepthCue_Start and _End distance (try 0 and 1000 inches, open result in GIMP/whatever, check min/max grey, put those figures back into Start/End, and rerender)
- disable glowing materials (ambient, reflection, alternate diffuse, others???)
- render (disable IDL/SSS if you use those to speed it up)
N.B. Don't forget to back up your scene first if you start changing the materials.
- Plug a P-Node into Atmosphere depth cue, leave the lights on, and don't touch any other materials...
http://www.renderosity.com/mod/forumpro/?thread_id=2821053&#msg3760699

The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.