PDA

View Full Version : Layering Particle Systems by depth for Live Action


martincutbill
11-30-2009, 08:34 AM
Hi,

How do you output two seperate render layers of a single particle system for compositing around a live action element?

Say I have a mini tonado spinning around a character -- how can I get the front and the back parts seperately to compisite behind and infront of my live action character?

Cheers!

Hezza
11-30-2009, 11:45 AM
You leave your character in there but with an all black shader on, so as the particles go behind him they are hidden.

EDIT:

Sorry, didn't read your post properly about the live action part...

I suppose you could do the same, track or roto a mask over the live action element, obviously much more difficult for a character than say a building, or do a depth pass maybe.

martincutbill
11-30-2009, 01:01 PM
I suppose you could do the same, track or roto a mask over the live action element, obviously much more difficult for a character than say a building, or do a depth pass maybe.
I've already resigned myself to having to roto out the character from the liveaction, ideally I'd like the nearer and further parts of the tornado on seperate layers so it's then a straightforward job to comp them behind and infront.

I guess putting a black card halfway though the particle system for one pass would give me 'front and back' (no card), which I could use behind the character, and 'just front' (card obscuring back) pass to lay over the top of the character...

Derek Wolfe
11-30-2009, 10:24 PM
I would use near and far clipping planes to get the effect you are after.

mandark1011
12-02-2009, 01:21 AM
yup near far clipping planes work really well or you can make an alpha matte of just your character then place a plane and camera project that image sequence onto the plane... been awhile but basically you are looking for that 2d plane to be black in your diffuse layers and not show up in alpha while still rendering with the image sequence alpha intact.... confusing.. probably but it works really well if your camera doesn't have too much parallax.

good luck!

CGTalk Moderation
12-02-2009, 01:21 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.