Reverse mask possible?

Ethan Winer wrote on 8/8/2007, 2:09 PM
Hi,

I've seen the tutorials showing how to create a mask that passes parts of the child track based on the presence of white in the parent track. But what I need is the reverse - to block parts of the child. I have a person shot full-frame on a green screen, and there's a narrow line in the wall-floor corner I couldn't get rid of. I hope to use a dash or underline to block that line on either side of his legs, but I can't see how to do that or which composite modes to select.

Thanks for any advice.

--Ethan

Comments

GlennChan wrote on 8/8/2007, 2:15 PM
Look in the Vegas help for the mask generator filter... you can use that with the multiply composite mode to control all your alpha and compositing stuff.

Bezier masking may come in handy too. I'm not sure what the exact configuration of all this should be, but you should be able to figure it out?
Ethan Winer wrote on 8/8/2007, 2:27 PM
Thanks for the fast reply Glenn, but I'm afraid I need more hand-holding than that. :-)

If I line up a dash or underscore on a parent track to block a portion of the child track, what composite mode settings do I use to make this happen?

--Ethan
GlennChan wrote on 8/8/2007, 2:34 PM
Er... you can use bezier masking instead of a dash or underscore??

I think you can simply do this:
Go into the clip's event FX and click the little triangles in the bottom left. This toggles the "pre/post toggle".
Go into the pan/crop for that clip.
Go into masking
Use bezier masking to get rid of the line. For each mask, you need to go into path (expand that tree branch) --> mode --> negative.

No composite modes, no parent/child masking necessary.
farss wrote on 8/8/2007, 2:36 PM
You can create a garbage matte in PS, just use the airbrush tool to paint white on a black layer on the parts of the frame that you want to keep.
Or as Glenn said, use a Bezier mask. One approach is to use a Bezier to roughly cutout what you need to keep and then use the CK to finish the job. The key thing with most CK is it's only the area immediately around what you're keying that needs to be keyed well. The rest use a number of techniques to get rid of, that's easy as no fine detail or motion involved.

Bob.
Ethan Winer wrote on 8/8/2007, 2:46 PM
Okay, thanks much to both of you. I'll play with this some more. As you can tell, I'm a newbie with anything other than basic video editing. But just knowing that a parent/child track is not needed gives me hope that this will be relatively easy to fix. I'll let you know tomorrow what happens.

--Ethan
DavidMcKnight wrote on 8/8/2007, 3:11 PM
Ethan! Welcome to the world of Vegas.

We've never met, but I used to read your posts on the prorec board and learned quite a bit, even for a retired bass player.

I encourage anyone who records audio to check out Ethan's website, given in his profile.

Welcome to this forum. It is *without question* the finest of its kind.
Chienworks wrote on 8/8/2007, 3:14 PM
I'll also point out that if you want to stick with using a line of text dashes or underlines, you can negate the mask in the text generator window by setting the text color to transparent and the background to white.
Ethan Winer wrote on 8/9/2007, 10:06 AM
Thanks David!

To the others - OMG!

I've been using Vegas 6 for quite a while now, but only learning what I needed at the moment to get the job done. I had NO IDEA you could draw positive and negative masks free hand! This is huge for me, and helps me with a lot more than just my current problem with green screen flaws around the edges.

So thanks to you all.

And I'm sure I'll be back for more soon. :-) I'm in the final throes of a huge (for me) performance video project I've been working on for more than a year now.

--Ethan