PDA

View Full Version : Green Screen - chroma key

Randis
10-31-2008, 02:53 PM
I am working on a new demo.
does anyone has usefull tips/advice for keying out the green screen?

i use AE 7 pro and Primatte Keyer Pro 4.
I edit p2 1920x1080 mxf files. i convert the mxf files with Raylight to AVI (default settings)

The recording was ok and lighting was good, however many objects are saturated with lots of green values, some scenes are a bich to edit.

are there any more sophisticated tutorials on chroma keying, maybe someone also have some good tips and advice.
I worked with green screen before, however that was a very different setting in a small scale, the BG was very even and clean and the object rather static. what i have here now are large scenes with many moving people, the BG is not very even and there are many objecs (marker, equipment) that have to be removed, everything on the scene is a bit affected by the large green screen so the whole scene has a lot of gree saturation.
The green color is a bit dirty, high yelllow values.

i do not have final cut, smoke and so on, please do not referr me to other software.

all i could find with google were rather simple beginner blue screen tutorials, good enough to make a homeclip for youtube but nonwhere close to a production quality.
aglick
10-31-2008, 03:21 PM
Google is a great place to start. I'm sure there are plenty of tutorials and tips...

I'll offer up a few suggestions:

-Get your "diffuse" lighting right
-have your talent properly dressed and/or props the right color
-use the right software tools (and methodologies)

Also, i'd suggest making sure any transcoded files use as little compression as possible. Go uncompressed AVI or QT for this part of your pipeline if possible. This will preserve the data from your P2 media which will result in easier/cleaner chroma/alpha keys.
Randis
10-31-2008, 03:43 PM
As i stated in my first post i didnt find any advanced tutorials.
I no longer have controll over the recording, it was done by someone else, i have to work with what i have.

i work with uncompressed files already btw.
aglick
10-31-2008, 04:09 PM
yikes! good luck.
capt chuck
10-31-2008, 04:37 PM
I don't know of any tips for the color bleed, but if you're having trouble getting the mask because of the uneven lighting I did see one tip that could help. The tip suggested when having uneven lighting don't try to keep sampling the green colors to add to the mask. Rather it suggested making several masks one based on a bright green sample, one on a darker, etc. Then combining the masks for the final composite. The tip claimed that you get an overall cleaner mask this way vs. increasing the mask sampling range.
Randis
10-31-2008, 06:26 PM
Thanks for the feedback. i am running some tests now
scrimski
10-31-2008, 06:55 PM
Post a frame of your footage.
vidina
11-03-2008, 08:02 PM
I have a tutorial over at aurellia (http://aurellia.net/tutorials-AE02.html) using primatte 3.0 on similar footage. You might want to look that up, aswell as maybe some matte choking.

Might help you out a bit, at least.
Pangea3D
11-03-2008, 10:13 PM
I just finished chromakeying 200+ shots of interview subjects on green screen. What a nightmare! The shots were came from 4-5 different production crews shooting at various locations around the country (US).

On many of the really horrible shots I was forced to rotoscope masks as a last resort. This may be a good option for you depending on your subject matter and time frame.

Good luck! =)

-Alex G.
CGTalk Moderation
11-03-2008, 10:13 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.