I'm trying to generate cigarette smoke moving through a room. I need to keyframe the emitter position and size properties, making it difficult to position and create a proper reaction with the displacement fields and a displacement layer.
Well, it's a pretty generalized "how do I do this" question. It's hard to tell what you've tried, or what problems you are having. Getting this to look right is going to be a mix of getting the right Base Form shape, Fractal Field, Flow, etc. So, if you were asking specific questions about what you are having difficulty with, you'd probably get more response.
What might help get you started is a basic smoke thing with Form that is posted here:
Thanks Harry. That'll get me started. I'm having the most luck with strings as the base with random opacity and size settings turned up. Fractal distortion is making it look smokey with some tweaks.
Mostly I need help displacing the form to a specific background plate. Since you need a displacement map that is the same size as the form emitter, it is difficult to prepare an accurate plate when moving the particle x,y,z position and size.