This is what happens when you work on multiple things simultaneously for long periods of time, your mind goes down rabbit holes and gets stuck on a path sometimes. I know, it sounds so obvious now in hindsight. I started messing around with placing my smoke in fog volumes, messed with custom proximity shaders, and then one day simply tried an area light. So I needed to find another way to cheat it.

There is a nice visual explanation of Deep Opacity maps here. Essentially the limitation is on C4D’s end I believe (no facts to back that up), because it cannot export Deep Pass files. The science behind why a native depth pass cannot be created makes sense to me, but it would be nice to as least get something for the base fluid object as if it was a solid form. Remembering back to a two year old post on the Jawset forums asking about TFD depth passes and being told it wasn’t available, I set out to find a work around. Recently I was creating some stock footage of smoke plumes for in-house use and had the need for a depth pass as well. You can see some of those experiments over on my Vimeo channel. I am a huge fan of this plugin and have been able to get some really great results from it. In this particular case it is the Fire and Smoke simulation plugin TurbulenceFD(TFD). In most cases with professional softwares it can be, but not all softwares support this feature. Creating a depth pass for a smoke simulation should be a simple task you might think.

Turbulence fd free