Multiplying by coverage is only half of it. You also need to get a 1-pixel edge around your "hard" matte, and multiply that by the inverse of the pixel coverage, then add the result to the first part. So:
Good Matte = (Aliased Matte) * Pixel Coverage + (1-pixel edge of Aliased Matte) * (1 - Pixel Coverage). There's a good chance that will be too much math in AfterEffects, and your compositor will give up. In Nuke, you can build a gizmo, and it ends up being pretty manageable. If you're working with someone else using AE, I recommend generating mattes for them (potentially using the coverage pass as described), to keep the complexity down in the actual comp. Also, keep in mind, this technique doesn't work well with semi-transparent objects, motion blur, or depth of field. It only solves the problem for hard cg edges. - Andy On Thu, Oct 18, 2012 at 11:15 AM, Byron Nash <byronn...@gmail.com> wrote: > Thanks for the info Eric and Ciaran. I will give that a shot. > > > On Thu, Oct 18, 2012 at 12:05 PM, Eric Lampi <ericla...@gmail.com> wrote: > >> Hey Ed, >> >> Here you go. They were talking about an ObjectID shader, but it seems >> like this is pretty much the same thing as the current Object Label channel. >> >> http://www.si-community.com/community/viewtopic.php?f=28&t=340&start=10 >> >> Eric >> >> >> >> On Thu, Oct 18, 2012 at 11:13 AM, Ed Manning <etmth...@gmail.com> wrote: >> >>> hey eric -- could you post the links you found? (I'm feeling to lazy to >>> google that string myself!) ;-) >>> >>> On Thu, Oct 18, 2012 at 11:03 AM, Eric Lampi <ericla...@gmail.com>wrote: >>> >>>> Murphy's Law applied to email lists, 5 minutes after you send off a >>>> help post, you find what you need. I did a search on ObjectID instead of >>>> Object Label after seeing someone refer to it... >>>> >>>> Thanks anyway, >>>> >>>> Eric >>>> >>>> -- >>>> Freelance 3D and VFX animator >>>> >>>> http://vimeopro.com/user7979713/3d-work >>>> >>>> >>> >> >> >> -- >> Freelance 3D and VFX animator >> >> http://vimeopro.com/user7979713/3d-work >> >> >
