PDA

View Full Version : How to put a CG model behinde something?

Gangstashers
12-15-2005, 03:06 AM
I was wondering how i can put my CG model behinde a person or a three or bushes?

I did use a old methode masking it in After Effects, copy the original layer put it below the cg intergrated footage and just mask.

but i found it dificult to mask it while it is going behinde a three or a croud of people.

Any ideas or easy way to do this?!

Thanks!


Sheherryar
Vympel
12-15-2005, 03:23 AM
Perhaps either possible to use keyers, "channels" combined with masks
Gangstashers
12-15-2005, 02:52 PM
I am not so familiar with all the options in After Effects. Could you perhappes explain me how like in step by step or short explenation?


Sheherryar
dprgb
12-15-2005, 05:12 PM
Basically no, there's no easy way to do it. You have to generate a matte / mask one way or another to incorporate CG into live action.

So, the best options are:

1. Paint a bitmap mask for every frame of the video (this could possibly take you forever).

2. Use bezier/polygon masks to create a mask on one frame and then animate the mask points over time (also known as rotoscope)

3. Use a keyer (chroma/luma) to try to automatically generate a mask. This works best when there is a big visual difference between the foreground and background elements in the shot.

There's no real short explaination - keying can become complex, roto work is time consuming. I don't know After Effects so I can't help you out with how you do it in those programs.
CGTalk Moderation
12-15-2005, 05:12 PM
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.