question for the experts...

[Sithxace]

This isn't something I am trying to do but I was just thinking. If lets say you have footage of a hill, and you have a 3d model of a bug. You create the bug climbing up the hill (easy). But has it goes down the hill, half its body will be behind the footage of the hill while the back half is still in front of the hill... how would you do this? I am having a hard time seeing a mask do this because if you have a mask used to hide the 3d bug as it is going over the hill, the mask would get rid of the 2nd half of the bug thats still climbing up the hill...

I hope ya understand what I mean.

 

[Loney Childress]

The mask doesn't have to be there the entire footage. You can start a layer just as the bug is to be cut off going over the hill, that way it won't cut the bug off as it climbs up to that point.

Are you making your bug aiming slightly upward and then tilt downward as it goes over? I'm trying to picture this in my head.

 

[Sithxace]

No, more like the body of the bug bends so the bottom half is still in front of the hill and front half is behind the hill

 

[Jim Montgomery]

Try masking the sky over the top of the hill and use a subtract mask, now anything that goes over the hill boundry will be subtracted from the scene. To replace the sky just duplicate the hill layer and place it underneath all.

Think that will work.

Jim

 

[Anhar_Miah]

heh, you simply model the hill plane in 3d set it to green, then when you render it, its perfectly masked in 3d space.

 

[Matt Grunau]

heh, you simply model the hill plane in 3d set it to green, then when you render it, its perfectly masked in 3d space.

Or, just texture the hill black and the bug completely white with the Luminosity all the way up and make a render of that. You use it like alpha information back on your original footage. No compositing that way, just track mattes.