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How to mask a background of an animated object?

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kim seng ngHow to mask a background of an animated object?
by on Jan 4, 2015 at 10:36:51 pm

Hi, I just started to use After effects but I can't figure out how to do the below.

I got a line drawing of cartoon animation (frame by frame animation), a line drawing of office setting behind the cartoon animation and a paper texture background.


Can anyone tell me how can I mask the office setting behind the animated cartoon please? since it's all line drawing, the office line drawing is now overlapping on my cartoon animation so I need to mask it out.

thanks in advance!


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chris brettRe: How to mask a background of an animated object?
by on Jan 5, 2015 at 8:35:33 am

Hi Kim

If you use the front animation as a track matte for the background that will key the front animation over the background though if your line drawing is 'hollow' you will still need to mask the middle in some way.

How you do this depends on what the front animation looks like - it might be easy enough to just animate a mask using the pen tool.


-------------------------- chris --


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kim seng ngRe: How to mask a background of an animated object?
by on Jan 5, 2015 at 10:29:21 pm
Last Edited By kim seng ng on Jan 5, 2015 at 10:31:36 pm

Thanks Chris,

the line drawing looks hollow but whatever is behind the front animation should be masked out.

Take a look at the attached. The guy will be animated in front of the laptop and I don't want the laptop overlapping on the guy's body while he is moving.



cheers


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chris bretth
by on Jan 6, 2015 at 12:24:37 am

Hi Kim

--- reckon there are a few ways of doing this and its probably not as hard as you might think ....

.... assuming you only have 50 frames or so to deal with I would key white over areas of the background where the overlap happens then key the character back on top.

This probably isnt as hard as it sounds and I would do it like this -

1 ) comp both line drawings together and render comp

2 ) import comp and draw green using a hard-edged brush over the lines where the laptop has crossed into the character - there is no need to be too careful just get a big brush and off you go --- as long as you do not go over the outside edge of the figure drawing you are ok.

Draw the green about halfway into he line which is the outside perimeter of the figure - this is important -- zoom in and get the green roughly halfway accross the outside line - that way you will get a perfect edge

-- this sounds like masses of work but you only need to be precise where the black lines of the laptop cross the outside edge of your character - all the inside detail of the laptop just splat it out and no need to worry about inside detail of character either because we are only using this clip to mask the background ----- the character goes back on top again.....

3 ) when you have done every frame render out

4 ) then make final comp like this ---

Key white over background laptop using the green from clip 2 ) as a key source - this should give you a white 'hole' in the laptop where the figure goes --- just key the figure back on top again and it should be a pixel perfect match......


------------------- all the best ------chris


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kim seng ngRe: h
by on Jan 6, 2015 at 1:40:06 am

Thanks Chris,
I have about 5 mins of animation so basically it will have much more frames.


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chris brettRe: How to mask a background of an animated object?
by on Jan 6, 2015 at 10:36:16 am
Last Edited By chris brett on Jan 6, 2015 at 10:37:45 am

Hi Kim
-------- thats a lot of frames !

-- have thought of a better version of the same idea which might help - you could try this --

1 ) key white over the laptop using the guy as a track matte making sure you shrink the matte slightly - this will give you a good outside edge of the guy to work to -- render clip

2 ) import rendered clip and paint out sections of laptop ( in white ) where guy is to go - working to white lines as rendered in ( 1 )
- depending on the animation you may be able to use an animated mask for a lot of this.

3 ) key guy back on top

----- a lot depends on the nature of the movement as to best method of painting out background lines ( to make a white hole for your guy ) but I dont think you have much choice - sometimes you just have to get stuck in ----

---------------------------- chris .


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kim seng ngRe: How to mask a background of an animated object?
by on Jan 6, 2015 at 7:19:02 pm

Thanks Chris, much appreciate it.


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