Moving Mask question

Steve Mann wrote on 5/27/2005, 1:29 AM
Problem - stage shot, talent is on stage but people are still taking their seats - walking in front of camera, of course. Talent on the stage is not blocked by the people moving in front of the camera. Good, I make a JPEG snapshot a few frames before the people step in front of the camera. I put this snapshot on a new track above the event. I used the Bezier curves to make a moving mask to replace the people moving in front of the camera with the still shot, but the talent on the stage is unaffected.

It looks pretty good - unless you're watching closely, you wouldn't suspect a thing. Except as the mask is moving to remove the people in front of the camera, the lighting on the stage fluctuates.

Question - Can I fix this so that the levels don't add together?

Thanks

Comments

Grazie wrote on 5/27/2005, 2:08 AM
All FXs are keyframabel over time. Is that what you wanted to hear?

Anyways! Kewl use of Masking .. Great Stuff! - Any chance of seeing a Before 'n After sample?

Grazie
Steve Mann wrote on 5/27/2005, 11:51 PM
Example - sure, it only lasts a few seconds. Heres a link to the before & after on my website:

http://www.mmdv.com/vegas/

My problem isn't the moving mask - that was actually easy with keyframes. My problem is that the luminance sems to be adding and you can see the mask if you know where to look. The intensity of the lighting on the stage changes in the after file, but it's constant in the before.

Steve Mann
Grazie wrote on 5/28/2005, 1:31 AM
OK .. What I did to make a sensible comparison of this was to download BOTH clips, put them onto tracks - one above the other - lowered the opacity of one to see the difference between both.

Yes there is a marginal - I'm not saying in anyway acceptable - but a marginal "drop" in the luminance. This "appears" to be following the "shape" of the BIGGEST body that moves in front of camera. Maybe, just maybe you need to get that area/period tighter to the shape in BEz? Maybe you have gone blur/soften too wide? Maybe if you select OUT rather than IN OR split between the two? I'm not too sure that you might also be getting a darkening effect with someone "passing" in front of the camera - even though, I guess you had it on Manual/locked-off exposure.

So, in summary:

1/- The Bez might need to be tighter

2/- The luminance levels in both clips may not be the same anyway.

3/- The other thing, which you too might be thinking .. hmmm... is that the "cutaway" Bez might in itself be doing something to the layers . . well stranger things HAVE happened! Maybe the two layers ARE in fact reacting to each other - when they shouldn't. - Are you ion V6 or V5 . .try and repeat this in V5 - yeah?

4/- Do you see values in scopes we could put numbers to?

5/- Could you give the t/c where you see this is happening? I have it on the timeline so I could track where exactly you are seeing this?

Interesting indeed!

Grazie