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Green screen problems

Last post 04-07-2011, 10:56 by bhurst. 18 replies.
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  •  03-31-2011, 5:48 465018

    Green screen problems

    Have just completed a sequence using green screen, but the footage I "green screened" is far to transparent and the background shows through. The controles allow for more transparancy, but not for less.

    Any thoughts on the subject??

    Ian

  •  03-31-2011, 7:05 465037 in reply to 465018

    Re: Green screen problems

    Can  you grab a frame from your green screen video, direct from the camera and post it as an attachment?

    Don 

  •  03-31-2011, 7:27 465040 in reply to 465037

    Re: Green screen problems

    I havent made a video as yet because just looking at it on the story line it not very good i.e. transparent.

    Also, not sure I know how to post a video to the site.

    Ian

  •  03-31-2011, 7:45 465044 in reply to 465040

    Re: Green screen problems

    You don't need to post a video, just take a frame grab of the video from the camera and post it as an attachment. Put the video on the timeline, do not apply any effects, and take a frame grab, save it to the desktop and attach it to your post.

    Don 

  •  04-02-2011, 9:38 465565 in reply to 465044

    Re: Green screen problems

    Any progress in grabbing a frame and attaching it to a post? We should be able to get a lot of information from the grab frame.

    Don 

  •  04-04-2011, 2:03 465827 in reply to 465565

    Re: Green screen problems

    Attachment: Grabbed Frame 2.jpg

    Have done a frame grab but dont seem able to add it as an attachment.

    If it comes out ok, please let me know.

    regards

    Ianb


  •  04-04-2011, 6:10 465859 in reply to 465827

    Re: Green screen problems

    The green "halo" in your screen grab is common unless the lighting of the green screen is perfect.

    The green screen (background) needs to be lighted separately from the subject so that the green color is uniform.

    Also, if the subject is too close to the green screen, the subject will cast shadows on the green, making it harder to key out.

    B

  •  04-04-2011, 6:26 465861 in reply to 465859

    Re: Green screen problems

    Attachment: GreenScreenSample.jpg

    In the attached screen cap, the keying is pretty good, but if you look at the subject's hands, you can see some green "halo." This is because the green screen background was not lighted exactly the same on that lower part.

    B

    Edit: Also, many green screens are not "true" green. You have to experiment sampling the green in your video using the eyedropper to get the best results.

     

     


  •  04-04-2011, 6:57 465867 in reply to 465827

    Re: Green screen problems

    Your grab frame attachment was fine.

    I would also like to see as grab frame of just you and the green background, no picture inserted into the green area.

    Check out this thread for many good ideas on Green Screen.  Here

    Don 

  •  04-05-2011, 5:59 466080 in reply to 465867

    Re: Green screen problems

    Attachment: Grabbed Frame 1.jpg

    Is this ok?

    Ian


  •  04-05-2011, 6:29 466090 in reply to 466080

    Re: Green screen problems

    No, what I am looking for would be the picture of you with the original green screen background, just the way you shot it originally.

    Before you make your grab frame, turn off the chroma key effect. Your grab frame should now be just you in front of the green screen.

    Don 

  •  04-06-2011, 1:41 466283 in reply to 466090

    Re: Green screen problems

    Attachment: Grabbed Frame 2.jpg

    Better?

    Ian


  •  04-06-2011, 1:54 466284 in reply to 466283

    Re: Green screen problems

    First of all I suggest to do some ironing Wink

    Second I suggest to illuminate the green screen consistently good. The lower left part is darker than the rest.

    Third I suggest to wear another shirt. I don't know how the color is called (petrol?), but it's to "near" to green. That's why in your first screenshot the tiger in the background is visible "through" your shirt.

  •  04-06-2011, 6:03 466323 in reply to 466283

    Re: Green screen problems

    That's the picture I was looking for. From this you can get a good evaluation of your problems. First, follow the suggestions given by Inglof. Also, here is thread with many suggestions for improving "green screen".  

     http://forums.pinnaclesys.com/forums/thread/453018.aspx

    Most of the problems occur because of poor lighting. The screen should be evenly illuminated. The subject needs to be separately illuminated so as to not cast any strong shadows onto the green screen background. When you watch the weathermen on TV you'll notice shadows on the background. This requires what's known as a "linear keyer" to accomplish this effect. The keyer in Studio is digital, not linear, so no shadows.

    An easy way to get good illumination is to setup your green screen out of doors. Pick a nice overcast day so that there are no shadows. Be sure to set the camera for outdoor lighting and "white balance" your camera on a white card prior to shooting. Stand as far from the green screen as practical. The closer you get, the more green splash you will have around the edges of the subject. The color of the clothing is critical. Stay away from any clothing that has any green. 

    When you do the chroma key in Studio, try selecting the green for background, then also try the "medicine dropper" and select the color from your actual image. This will usually give better results.

    Let us know how this works for you.

    Don 

     

  •  04-07-2011, 6:06 466545 in reply to 466323

    Re: Green screen problems

    Thank you all for the input.

    I can now see that the condition of the green screen and my shirt colour has not helped the situation.

    I will try again whit all of your suggestion in place and post the results.

    Once again, thanks for your help.

    regards

    Ian

  •  04-07-2011, 6:27 466549 in reply to 466545

    Re: Green screen problems

    YesSmile

    Don 

  •  04-07-2011, 6:30 466551 in reply to 466545

    Re: Green screen problems

    You're welcome Smile
  •  04-07-2011, 8:10 466575 in reply to 466545

    Re: Green screen problems

    Like the others have pointed out, lighting is everything. I've been working with green screen for about a year now and learned this the hard way. Here are a couple of videos that have good information pertaining to lighting and filming with green screen...

     

    Here is a link to a video that talks about various lighting from budget to studio setups. http://youtu.be/n_2j75pySDw

    Here is a link that gives you an overall view of chroma key setups and tips. http://youtu.be/M_WdLkaOUic

    Hope this helps.

  •  04-07-2011, 10:56 466623 in reply to 466545

    Re: Green screen problems

    Attachment: IMAG0115.jpg

    FWIW ...

    I do a lot of green-screen stuff at work, and I just finished installing lights in my new green screen area. I try not to spend too much money, so I mounted some inexpensive track lighting vertically on each side of the screen to try to get even lighting.

     B

     


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