I’m having some problems with keying out some footage I have. there’s some artifacts of the green screen that bleed over on to the skin and pants. I tried bluring the key mask but then I loose alot of the detail on the edges and it looks shawdy(like the poo).
I’m keying with the hls mode instead of R.G.B.
Anyone have this problem and know how to fix it?
Green keying screen help.
azozel
#1
Vympel
#2
It would be interesting that you post a frame of the clip , try to use the Spil suppressor ? That operator you are using?
azozel
#3
ok this is my site that I just threw up for this thread.
http://junk-pic-poster.50megs.com/
Go to the photos page.
azozel
#6
Humm that helped a little but I’m still looking for somthing on green screen.
I’m still getting the fuzzy hailo and I’ve tried everything.
Has anyone ever keyed on green before with combustion3?
hemmerli
#7
nop -you are the first one … 
ok, a bit more serious. well, dv recorded to tape is one of the worst things to key, but as usual, alternatives were not at hand, so you have to live with what you have.
i could only play with the picture you provided in that link…so, some thoughts:
during shooting, did you had “edge enhancement” (camera setting) on? judging from the bright rim visible around her left side. if so, you shouldn’t do it again -at least not when shooting green screen. i don’t know the location, but for my tast, she stands a bit too close the the backdrop. her (blue) jacket has actual more green color than blue. judging from the link-pic the green values are everywhere 10 to 20 higher than the blue - can be different in the original footage,though. it just makes cc later a bit more difficult. i don’t know which camera you used, but the overall picture looks a bit soft. reason could be the camera lens (camera electronic to a lesser extend). if you want to continue to do more green screen work with your dv-cam, you might want to invest in a special videocard from aja or decklink or bluefish. use the analog s-vhs of your cam and digitize with one of these cards direct on location to the hd of your computer.
with the footage you have, make a garbage mask around your talent (just a coarse mask) and if necessary animate it. i used the yuv keyer mode -you might prefer the hls. try to make a good key. shrink and erode the matte.avoid the area between her upper legs. this area is more orange than green. select this area with a draw selection tool, if necessary animate the selection (the selection doesn’t has to be tight). apply a second keyer to this part. you might find it other areas which needs also special treatment, so, you might want to use more selections right to beginn with (like the area around her shues).
for cc/de-spill you might need to create a soft edged selection just for the edge area … goes like…create a new branch… use the original matte and shrink it one a bit, blur it, substract it from the original (in this branch) and use this newly created “edge” matte as the source for a compound selection in the branch with the keyed footage. apply a de-spill than. maybe you also need to create further selections.
well, sound like a bit of work…but if the original footage is of low-end quality -that’s only keying wise!!!- you need to do more in post
cheers,
-rayk
VFX_Follower
#9
For keying DV footage, I have had the best results using the YUV color space in the Discreet Keyer. YUV provides a softer key for your footage. Even though DV is not good for keying, you can create a decent key if you follow some of these suggestions:
First of all, if your source footage is poorly lit, then it doesn’t matter what it is shot on, you will have a difficult time trying to key it. I checked out your sample image and it appears to be lit pretty evenly. The only thing that I could see wrong with it is that there was not enough seperation of your foreground subject and your greenscreen. What I mean by seperation is two fold: the distance that the person is standing away from the greenscreen and the lighting of the subject. The lighting looks good, but there is alot of green spill on the subjects jacket.
Another thing to consider is the color of clothing your subjects wear in front of the greenscreen. It’s basic color theory from there. Blue is right next to green in the color spectrum. That is why you are getting halos around certain parts of your subject. The Discreet Keyer is a good keyer, but it is difficult to key the spill on the jacket without loosing alot of detail.
Now that is out of the way, check out these links for some help:
http://www.fxguide.com/fxtips-223.html
http://www.fxguide.com/fxtips-171.html
These tips helped me when I was keying. As a matter of fact this site is a great resource for compositing tips.
Now, I did notice somethings that were wierd in your composite. First of all, it looks as if you did not interpolate your footage correctly. There are interlacing artifacts on your footage. By correcting this at the footage level, in the source tab, will greatly help your key. The other thing I noticed is that your composite is set as 16 BIT. As long as your DV footage isn’t interpolated as having a source bit-depth of 16 bit, you will be okay. DV is natively 8 bit. You can work at 16 bit but you will not see any improvement in your DV footage. Working with high resolution sources from film footage, still images, gradations and particle effects generated in combustion will look good at the high bit-depth, but you are going to add significant rendering time in the end. Combustion is a resolution independent compositing system, but you cannot convert 8 bit to 16 and expect to have the same type of control of your DV footage, as you would with native 10, 12, or 16 bit sources. So, if DV footage is the only type of footage you are using, I would suggest sticking with 8 bit setting for your composites.
I know this is alot to wade through, but I highly suggest you check out the links above and play around with the settings. Every composite is different, so the time you spend experimenting with keying footage, the better prepared you will be for the next time.
I hope this has helped point you in the right direction.
Cheers,
JB…
azozel
#10
:bowdown:Thanks a ton man you have no idea how much this helps.
Just a little backstory on the footage. It was shot in over a 6 hour period in L.A. then flown back to virginia. So the footage I’m working with is a one shot deal. I wish we could do a reshoot.
I’ll post some more results soon.
Thank’s again you are the man. and it’s good to find somone who really knows what there talking about.:bowdown:
VFX_Follower
#11
No problem man, glad I could help. I can’t wait to see some updates.
Take care,
JB…
roto_baggins
#12
when i pull keys i use two mattes, a hard and a soft matte. the hard for the fill and the soft for the edge and hair. as we all know each shot is not the same and requires different techniques. goodluck!
azozel
#14
I’ve posted an update pic for those who are interested. With the Background it looks very nice. But due to legal resions I am unable to post the final composit.
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