Rotoscoping Woes

[Millionflame]

Hello all,

My problem is that when I use Bezier nodes to rotoscope out certain things sometimes they work, and sometimes they don't. I have no idea why it's hit and miss because I have the same flow and settings for everything.

I use the Bezier and set it's output to the alpha channel. Then I premult it on the rgba channel again.

I've used this exact same way to take out things from a rendered pic / elements, but sometimes it does nothing.

Is there another way to rotoscope, or what else is going on?

Thanks for the time,
A.

[nathan]

I noticed that you are piping a node that already contains an alpha channel into your bezier node. Your bezier is only going to add to the alpha channel in that case so if you premultiply after the bezier you are not going to get the same affect as if the input of the bezier doesn't contain an alpha channel. You could either check the "Replace" check box for your bezier node or use a merge node with the mode "out" or "in".

This might not be the problem however, it is a little hard to tell just by the one picture you provided. Could you explain a little more or possibly post an example scene file that shows the problem?

[Millionflame]

Hmm, nope didn't work like I thought it would.

I was putting together an "example" scene when I noticed that it was working in there, but not on my main scene.

Going to try and replicate the problem, or hunt down the problem in my main scene first.

[Millionflame]

Ok, I got it to work with the "out" mode on the merge node. Also, everything upstream was causing the alpha channel to go haywire, so I fixed that and now it works.

Thanks again for the help. :)