FORUMS: list search recent posts

Using Videocamera for greenscreen footage.

COW Forums : Cinematography

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Robert Penczak
Using Videocamera for greenscreen footage.
on Nov 7, 2011 at 9:24:48 pm

Hi, I have a JVC Everio GZ-MG750BU camcorder which I've been trying to use to record some videos against a greenscreen. The video l9ooks fine till I bring it into After Effects CS4 and use Keylight to pull out the green background. At this point, despite using techniques from a number of tutorials, I'm left with distracting, wavy edges. Below is a link to the page where I posted a bit of the video. I added a yellow background to make the problem stand out a bit more.

http://www.drupal.yourgods.com/greenscreentest

From the Adobe forums, it sounds like the problem is the compression that occurs on consumer end video cameras. My camera does not have a firewire port, just a USB connection, an internal hard drive, and an SD card.

Questions:
1) Would recording to the SD card and using that to get the data to my computer avoid any of the artifacts that occur when connecting via USB? (someone at Videoguys.com thought that might be the case but wasn't sure)

2) Do the newer videocameras using AVCHD suffer from this same problem? (I read some articles that talked about compressing things down to varied rates from 4:4:4 to 4:2:1 or less where instead of retaining all the luminance and color data, much was dumped before getting saved when using HDV format)

3) Any fairly inexpensive videocameras now available (to look for during Black Friday sales) that work well for greenscreening?

Thanks for any suggestions.


Return to posts index

Mark Suszko
Re: Using Videocamera for greenscreen footage.
on Nov 7, 2011 at 9:49:18 pm

Robert, you don't really give enough data to be sure, so it could be any number of things, from how well you lit the scene and the screen, to the codec you picked to edit in on your NLE, to the code used in the camera. The Everio is alovely home movie camera, but I wouldn't expect great chromakey from it's footage. As you say, better keys come from a wider color space, preferably 4:4:4.


Return to posts index

Angelo Lorenzo
Re: Using Videocamera for greenscreen footage.
on Nov 7, 2011 at 9:50:46 pm

1. Shouldn't make a difference. Regardless of the method, you're transferring a file to your computer, not much different than using a thumb drive basically. There is no degradation in quality. Whatever you heard on Videoguys.com is misguided... it's not like you're capturing from tape.

2 & 3. Hard to say, I don't watch consumer camera models and specs.

I would suggest, however, doing a few things to improve your key with the camera you have. Take these with a grain of salt as I haven't seen a "before" so I don't know if you're lighting or exposing the green screen with any proper technique.

1. Light the green screen as evenly as you can. You can light it +/- 1 stop from whatever proper exposure is for your setup. This is assuming you have manual controls on the camera, you may not. In small spaces I underlight a little bit to reduce spill.

2. Garbage matte the majority of the greenscreen. There is no reason to crank up your key settings to remove a wrinkle in the corner and let it destroy the overall quality of your key.

3. Set one key to remove the majority of green around your subject. Use modest settings. Don't worry about green fringing.

4. Add another Keylight effect and finesse it's strength to remove the green fringe.

It won't make a perfect key, but I have a feeling it'll be much more acceptable. Pick a busier background and your subject's edges will look a bit better too. Testing on solid colors can drive you nuts.

Angelo Lorenzo
http://filmsfor.us - Helping you sell your film online






Return to posts index


Mark Suszko
Re: Using Videocamera for greenscreen footage.
on Nov 7, 2011 at 9:53:23 pm

A magenta backlight will help counter green spill and help with edge problems. When using blue screen, the proper counter-color for the backlight would be amber.


Return to posts index

Robert Penczak
Re: Using Videocamera for greenscreen footage.
on Nov 7, 2011 at 10:16:37 pm

Mark & Angelo -

Thanks for the replies.

I'm doing this in my home office against a 4' x 8' piece of hardboard painted green with two halogen workshop lights, one positioned about twelve feet away to light me, and a second positioned behind me and shining on the greenscreen at a dimmish setting to avoid blowing things out. Also have a separate, regular bulb light about 5 feet in front and off to opposite side as main halogen lamp to kind of serve as a Fill light.

I'm recording in HDV, but the Everio saves to its own MOD format which can't be directly opened inside of After Effects or Premiere Pro (I have CS4) - so I've been working with compressed footage (.wmv) which are roughly 25% the size of the original footage.

I'd read through some online stuff looking for a good way to get things out of JVC Everio's MOD format (from simply renaming the file type to downloadable programs), but I still don't have a good solution for this - so if someone knows a good way to get this to uncompressed AVI, please let me know.

I'll try another test video tomorrow or Weds with a couple of your tips in mind, and I'll post both before and after shots (pre and post kelight keying) so you can get a better sense of what I'm working with.

Thanks for the help.


Return to posts index

Robert Penczak
Re: Using Videocamera for greenscreen footage.
on Nov 8, 2011 at 1:02:21 am

Ok. I uploaded a pair of short video clips to http://www.drupal.yourgods.com/greenscreentest - the first shows the intact greenscreen after garbage matte, the second shows results of keying.

Note, I found a helpful plugin over at http://www.aenhancers.com - under their animation presets - stickeyed near the top of the list is "A good keyer for DV using Keylight - halfway through the thread there's an update for Keylight 1.2 in AFX CS4.

Still some shifting colors/light inside of my hair that I'd like to fix, but less distracting than the severe edge problem I was getting previously.


Return to posts index


Mark Suszko
Re: Using Videocamera for greenscreen footage.
on Nov 8, 2011 at 4:13:17 pm

Quote: so I've been working with compressed footage (.wmv) which are roughly 25% the size of the original footage.


Yikes. I think you found your main problem.


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]