Compositing cycles fire and smoke

Support Compositing and Post Processing
1

Hi guys,

I’m trying to composite some fire and smoke on top of a real world clip. I’m having issues though, the fire ends up looking very wierd when I composite although it looks nice in the 3d preview render:

fireissue2.png768×847 315 KB

I think it has to do with alpha channels. I tried to hack up something with the node editor to make it so that the smoke has a correct alpha channel, because if I just use the one provided by the render layer, it’s empty. This is the setup.

fireissue.png1723×854 189 KB

I’m a total beginner when it comes to compositing so I appreciate really any tip that you guys have to give me. Thank you immensely,
Bumbaz

2

Seems like an odd setup. Is your composite screenshot with this node setup or is that just 'alpha-over’ing the ufo layer on the background? From your nodetree, the ufo alpha channel looks ok…

3

Thank you for the reply, Hammers. I simplified the node setup a fair bit:

[ATTACH=CONFIG]345435[/ATTACH]

However, the render is just straight up ignoring the alpha channel of the fire. The UFO and the fire are in the same layer. This is what I get:

[ATTACH=CONFIG]345436[/ATTACH]

Strangely enough, the fire does show up in the final composite using the node setup I just posted, but not when it’s over the white sky:


I really don’t understand what I’m doing wrong at this point!

4

Unfortunately your node tree image attachments aren’t working so can’t really tell what you’ve done. Sorry if this is obvious, but have you tried just the ufo/fire layer alpha-overed on the background plate?

Try posting your compositor image again or even a blend file for us to look at.