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Creating a mask from a locked off shot.
I’m making a short little sequence for a programme where you see seven ladies with dogs sat on a bench, who throw a ball and all run off at once. Thing is, it’s the same lady and dog filmed seven times in different places, and I need to comp it together so it looks like they were there at the same time. I COULD do it by keyframing masks, but wondered if there was a more intelligent way of doing this? My hope is that I can use the locked off shot of the bench to allow FCP to see where the lady is and cut out the background for me, like the photobooth software on macs does with the isight camera. Any ideas? Images included in case I make no sense!
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8 Replies
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I hate to say it Michael, but this would have been a perfect instance where green screen would really have made this duck soup, but now I’m afraid you’re in for some serious keyframing. Shouldn’t be terrible however as long as your lady doesn’t collide with herself, and of course you need to color correct to match each instance very closely and soften the edges.
David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los AngelesPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
A forum host of Creative COW’s Apple Final Cut Pro, Business & Marketing, and Indie Film & Documentary forums.
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Use crop with feathered edge? Biggest challenge is matching each shot’s video parameters (gain, black level, etc,) so the image around each lady doesn’t look different from its neighbor. In your image the two outside ladies look pretty good, but the inside ladies don’t match well. I’d try the 3-way color corrector or Color to make the match. Keyframing masks would be a lot of work.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870
ATTO ExpressSAS R380 RAID Adapter, PDE Enclosure with 8-drive 6TB RAID 5
24″ TV-Logic Monitor
Final Cut Studio 2 (up to date)Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN
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There is a difference matte in the Effects>>Key library. I’m not sure how precise it is, but it’s worth a try.
As far as rotoscoping seven instances X 30 frames/sec x 30 secs. = 2700 frames. Unless you’re getting paid, don’t even think about it.
David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los AngelesPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
A forum host of Creative COW’s Apple Final Cut Pro, Business & Marketing, and Indie Film & Documentary forums.
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What you’re looking for is called a difference key. iChat has this built into it: step away from the isight camera a couple seconds, it grabs a still of the camera’s POV to use a “plate”, then you sit back down and it compares the live camera to the memorized plate and replaces only the pixels that are different, so it looks like you’re ichatting from a beach, roller coaster, etc. Looks like a rougher version of chromakey. I know AfterEfects has a difference keyer, but I don’t think FCP does. Perhaps Apple Motion has one though.
I’ll tell you though, that doing this using just the cropping tools in FCP should work pretty well too, and not need all that much if any keyframing, if there is enough gap between all the ladies and dogs so that they don’t overlap. If there is overlap, you’re going to have to rotoscope, or at least draw out some masks.
Do what you have done so far, go into the motion tab and soften the edges of your crops to blend the seams a little more, and you’ll have to tweak the color/brightness/contrast on each layer to even out and allow for changes in sunlight.
Another way to attack this if you lack a real compositor is to do it as a strip of tiff stills in photoshop. Export using quicktime conversion as an image stream, plus a plate shot of just the bench without anyone in it, use the power of photoshop’s layering and masking/selection tools to clean everything up, export as flattened tiffs back to FCP, they should drop right back into your timeline perfectly. Is this tedious, well, yes, however, maybe not as bad as you fear, if you understand how batch actions work in PS. You can record what you do to one frame and have it automatically repeated to all the othes in a stack or file, in seconds or at most minutes.
This way you could use Photoshop to quickly roto the ladies and dogs with alpha channel around them, then re-composite everything in the FCP timeline, or composite everything in Photoshop the “old fashioned way”.For something that’s only thirty seconds long, it is not unbearable… get the ipod rocking, a fresh 2-liter of Jolt and a fresh nib in the wacom graphire stylus, and go to town… by the time you come out of the trance, it’s done. 🙂
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It falls into my day job as an online editor at a small indie, so yup, I have to do it. I’m pretty reasonable with AFX, so doing it the long route with keyframed masks. It took me just over an hour to get about a third of the way through, and it looks pretty decent so not too bad! I hoped there would be an easier way but never mind!
Cheers!
Michael Lansdell
Online Editor,
Available Light Productions LtdMy system:
2 x 3 GHz Quad-Core Intel Xeon
5GB DDR2 RAM
512MB ATI Radeon X1900 XT
OS X 10.4.11
Final Cut Pro 6.0.4
Blackmagic Design DeckLink HD Extreme (6.6.2) -
“As far as rotoscoping seven instances X 30 frames/sec x 30 secs. = 2700 frames. Unless you’re getting paid, don’t even think about it.
“DO think about it, for just a sec.
The more you try some of this, the faster and better you get at it. It may be worth trying once, just for the fun and experience of it. To roto one of the ladies in PS, you could use the color sampling selection tool and get rid of 80 percent of the unneeded area with one touch. Not too shabby. And for the ladies you don’t even need a very detailed mask at all, 90 percent of each one is a batch job; after you do the first frame, I would guess the first frame of each lady would take me five minutes and then I’d batch the rest of each lady’s files with the recorded steps from their first frame, that batch might take three or less minutes to run on my old computer. Much faster on my eight-core.
Batch actions are very powerful: the first time I rotoed every frame of a thirty-second spot, it took me three days. Same exact job after learning to batch; around twelve minutes. Learning the better way to do it gave me freedom to try multiple styles and looks, and the best part of that is the ones you like you can save and re-apply to other footage as if it was a plug-in.
Little did I know in kindergarten, that my entire adult career depended so much on the ability to color inside the lines!
🙂
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This would be a terrific subject for a tutorial.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870
ATTO ExpressSAS R380 RAID Adapter, PDE Enclosure with 8-drive 6TB RAID 5
24″ TV-Logic Monitor
Final Cut Studio 2 (up to date)Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN
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If using AFX is an option, and you have a plate of the bench with no ladies on it, then you may consider using a difference matte. This by itself usually won’t give you satisfactory results. Most likely you will want to add blur and levels effects to the resulting alpha channel from your difference matte, then apply it as a track matte to an untreated duplicate of the footage.
If using this technique, it may also be helpful to color correct all of your footage before applying the difference matte. You will need to pre-comp or pre-render the color corrected footage before applying the difference matte.
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