i just needed to create a displacement map from geometry for later use. luckily, i happened to find this tutorial pdf from nomeradona (sorry, i googled straight the pdf, no tutorial page in between) and created a scene which could be reused with other geometry - and i thought i would share.
for this scene to work straight away you'll unfortunately need VRay.
however, it is definitely usable in other renderers too - two important information to know is that the red base plane is at Z = 0, and therefore the camera's distance equals the Eye Height (obtainable through the standard SU icon ). the other information is that this scene is set up to maximum geometry's height of 10cm (25.4 inches). these two values should set you up. oh and be sure to check your output aspect ratio and/or resolution.
of course, some post-processing of the resulting render is needed; but i think it's easier to post-process than to create from scratch
i'm attaching the scene file, i hope you'll like this addition.
PS: and of course, any additions/suggestions are most welcome, following the spirit of open-source