Keying Question

[taylormade]

I'm doing a 3D animation sequence from a series of PNG files made in Poser. The PNG files have an alpha channel built in and they key fine with one slight exception. The is a very thin line around the object that is very noticable because the background is a dark night sky. I Photoshop I can shrink the key by a pixel and get rid of the problem. Is there any way in AfterEffects to do the same thing? I really don't want to have to take each frame into Photoshop and rework them to fix the problem. I know you can refine the edges in a greenscreen key, but how about a frame with a built in alpha channel?

 

[bgodoy]

You can use the simple choker effect to achieve what your looking to do. Depending on your animation, this might or might not be ideal... However, it would help if you posted a screenshot to better determine what your options are.

If your image is touching any of the borders you will have to most likely mask the parts that get cut out back in. Hope this helps.
-B

 

[taylormade]

Okay, I figured out the problem. I was not rendering my 3D animation over a black background, so the edge pixels were picking up the lighter background and creating the lighter/white edge in the composite. I rerendered the animation over a black background and the problem was solved. I also tried the premultiplied mode for the alpha and changed the color to black, but this gave me very jagged edges in the key. Had to spend some time rerendering, but the result was worth it.