Height & Depth Compositing

I have had several requests over the past few months to go over how to do a fake fog pass using a height and depth pass in compositing, so I will put together a tutorial and post it here. I was working on a Macro for Digital Fusion, but I have run into several issues with dealing with curves, that I have to put it on hold for a little bit. For whatever reason, LUT aren't working properly from inside a macro. Anyway, I should have the tutorial posted here in a few days.