Comp premultiplied 3D in PS without matte lines

[jfrancis]

http://www.digitalartform.com/archives/images/cgObjects4Comp.jpg

http://www.digitalartform.com/archives/images/rightWay1.jpg

http://www.digitalartform.com/archives/images/rightWay2.jpg

http://www.digitalartform.com/archives/images/rightWay3.jpg

http://www.digitalartform.com/archives/images/rightWay4.jpg

http://www.digitalartform.com/archives/images/rightWay5.jpg

http://www.digitalartform.com/archives/images/wrongWay1.jpg

http://www.digitalartform.com/archives/images/wrongWay2.jpg

http://www.digitalartform.com/archives/2005/10/compositing_pre.html

[Datameister]

Good to know. Thanks for posting it.

[negativespace]

Thanks, I was having problems comping my images in PS and this worked great.

[jfrancis]

There actually is a better native PS workflow I've since become aware of:

After you have the element above your background "the wrong way," do this:

LAYER > MATTING > REMOVE BLACK/WHITE MATTE

...
If you do that, PS will do the divide for you and set up the whole thing in its preferred "straight alpha" style.

As much as I dislike straight alphas, when in PS, there's no fighting City Hall. This way is better than my way above because if you later decide to paint on the beauty pass using my proposed workflow, and your new painting goes outside your previous outlines, you somehow have to propagate that painting down into the holdback matte layer -- which PS isn't really set up to do.