GREEN SCREEN: hair keying question

B

benandaim

Well-known member
Hi,

I've shot some green screen footage in DVCPRO50 25p and rendered it out uncompressed from PP CS3. When i bring it into AE CS3 and key the green out with keylight i can get a great key tweaking the regular controls with no issues except i can notice the hair is a little bit jittery or flickery. Is this normal and do i just live with it or is there a trick to make the hair clean & crisp.

The screen is evenly lit and and one click of the colour picker does wonders to start me off with the key.

Any help & settings would be great. :Drogar-BigGrin(DBG)

Ben.
 
I've had that same issue in FCP as well. You can reduce the flickering but you may have trouble getting all the green out. It depends on the kind of hair and if there's actually green light reflecting onto it.

I just tweek the settings a lot until I get an image I can live with. I'm sure there are other filters that can be added to reduce the green on the edges.
 
I have all but stopped using green for video. Im finding I can get more even keys with blue. Usually I light bluescreen about one stop below subject.
 
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Cool two tips.
I have a reversable screen so i'll try blue & also try 1080p. Thanks guys, also in my case the hair had no green reflecting on it.
 
That's interesting. I read somewhere the green was best because of the higher sampling of the green channel. Don't missunderstand, I'm not doubting you just a little surprised.
BTW, what about exterior shooting with chromakey, I may be wanting to do this in a movie I'm working on (Very early days of pre-prep, scriptwriting).
Cheers,
Dave
 
Hey i just realised when i click keylight on the green for the first time, it keys a bit of the talents yellow name badge out?

What the?? Does anyone know why this happens, this badge looks nothing like green!
 
Use light Magenta for talent Backlight

Use light Magenta for talent Backlight

I came in late on this and someone may have already addressed this but I've always used gels on backlights to reduce screen bounce on talent. For Blue Screens, I use a straw or very pale yellow backlight as yellow is the compliment to blue and a pale yellow shows up as natural light or even white on video.

For green screens I use a very pale magenta as my talent back light as magenta is the compliment of green and just as with yellow, it appears as a natural light source.

Both these techniques have been very good in reducing if not eliminating all screen bounceback. And it's good to keep your talent at least 5 -6' away from the screen too. Roscor makes a good light correction selection of gels that work really well for this purpose.

For more info, go to http://www.lowel.com/edu/ as they have a succinct online tutorial on this and other stuff light related.

Also for color changing/correction you might want to look into some keying software called AdvantEdge which is made by Ultimatte I believe. You can isolate colors and change things like blue ties, yellow badges, etc. and allow for clean keys on your subject. There's a great article on practical keying scenarios in DV magazine: http://www.dv.com/features/features_item.php?articleId=196602532



Good luck.

Chuck
 
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They are great tips !

I've pulled some pretty crazy keys before, not HVX, but Digitbeta SD video. We even had a Yoda puppet who was an olive green key nicely off of a greenscreen. Sounds crazy but when we shot, we had so many blue costumes and only time for one set up that we had to run with a green.

So glad it worked out in the end. you'll be surprised what you can key when your DOP does a great job !

Richard
 
These edges are still a bit of a problem.
They almost look rippley or wavy. I've since read a few more tutorials on how to use keylight but they seem to use the settings i'm already using. I'm just not sure i could put these keys to air, any other suggestions or experiences would be great!

Ben
 
Don't shoot DVCPro25 for keys, instead Shoot DVCPro50. (or HD 1080)
For green use high exposures for green level 55- 60 IRE.
Lower detail to -1 or -2 even -3 if you dare.
Raise detail after the keys have been cut.
 
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