How to render additive fire pass and smoke pass?

Workflow
1

I’ve setup a simple missile launch from a helicopter. I composite all the layers in After Effects. So I’ll have the background, the helicopter, the missile, and hopefully a fire pass that will be set to additive, and finally a smoke pass. I’m not sure how to isolate the fire and smoke for rendering those passes. My gut tells me to turn off all the lights and make the smoke black to get the fire pass, but I’m not sure about the smoke. Do I turn off the fire? How do you layer it in the composite, just drop the fire right on top set to additive?

Appreciate any advice. I’m going to keep moving forward but would love to hear how folks are setting this up. BTW I’m doing this in LW 2015 using Build 1466. I know, old build and old 3d software, but it’s what I’m working with since newer versions of LW break turbulence FD and I haven’t learned Cinema4d yet. I’m still able to produce some awesome stuff, just new to fire composites.

Thanks again.

2

Render separate atmosphere passes of fire and density and them composite those. Experiment with different alpha settings. You can also use other channels in the opacity maps for even more variety. And of course you can get multiple renders from fire and density, multiple colours etc, by adjusting the function graphs and narrowing in to various ranges .Sometimes an atmospheric pass of the illumination from multiple scattering makes a very good additional pass. I use fusion so cannot be of much help with AE. To be honest RS and Arnold do such good GI renders of Volumes I tend only to use the passes for additional looks relying more on spending the time getting either RS or Arnold to look close to final and then tweaking in comp.