GREEN SCREEN background replacement

M

msjenkin

Member
Im working on a short film project and one scene is a surreal/dreamlike environment. It takes place in a bedroom. I want to put a green screen on the outer side of the double bedroom doors (image #1 attached below) and then key in an exterior shot of a snowy forest. Similar in effect to image attachment #2. Any tips, advice, or best practices? The exterior shot will be static but there will be action and movement within the shot.

Any help would be appreciated!
Thanks
Michael



Bedroom Doorway.jpg

zathura-3.jpg
 
If I understand correctly what you want to do - i wouldn't use green screen at all. You deal with straight lines only, and it's super easy to mask out everything between the doors. You need literally several seconds to do that.
 
David Saraceno said:
Just use a static mask

View attachment 95676
Click to expand...

That's what I thought and said. Now I'm thinking that he wants to shoot some action in the room itself for example people or cats/dogs, etc. Obviously masking the opening will not work in this case. If this is true, I'd simply shoot the whole thing with green screen and used the room (with already processed door opening) as just one background.
 
OK thanks for the advice, if I wanted to have the camera moving inside the bedroom, would that change your opinions as far as static mask vs green screen? We want to shoot from a high angle like the photo above, but may be shooting from a crane so movement may be likely. I'm wondering if a moving shot would make a difference for the static mask?

Thanks!
 
silyn said:
That's what I thought and said. Now I'm thinking that he wants to shoot some action in the room itself for example people or cats/dogs, etc. Obviously masking the opening will not work in this case. If this is true, I'd simply shoot the whole thing with green screen and used the room (with already processed door opening) as just one background.
Click to expand...


Ok sounds like if I am going to be having action in the room itself (or moving camera) I would want to go with green screen?
 
silyn said:
That's what I thought and said. Now I'm thinking that he wants to shoot some action in the room itself for example people or cats/dogs, etc. Obviously masking the opening will not work in this case. If this is true, I'd simply shoot the whole thing with green screen and used the room (with already processed door opening) as just one background.
Click to expand...

I agree. If the cam isn't locked down, he will need to need a green screen.
 
msjenkin said:
Ok sounds like if I am going to be having action in the room itself (or moving camera) I would want to go with green screen?
Click to expand...

An action in the room and simply moving the camera are two different things. If something is going on in the room itself like moving objects ( regardless of whether the camera is moving or stable) you will need a green screen approach.

If you move only the camera ( but nothing else moves inside the room) you can still go with masking. This is true even you want to have some parallax visible (when you move the camera inside the room the image in the door opening is shifting). But with parallax visible, you will have to use a compositing software like Adobe AE, Nuke, etc. - you will not be able to do this in any regular NLE (FCP X, Adobe PP, etc.). In this case you can still mask the opening, but both layers (the room and the sky background) should be set as 3D layers and should have different positions on Z-axis. And obviously your sky background should be larger that the door opening to account for the parallax shift when the camera moves.

And a final piece of advice if you go with compositing - do all your camera movements in compositing software since it will be much easier (because if you want to reproduce complex movements of a real camera you will have to do camera tracking which will require very good compositing skills).
 
Don't forget tracking markers - if you'll use the 3D tracker, get some in the Bg and make sure there are foreground elements that will track - TEST TEST TEST!!!

Also, I should add - TEST TEST TEST!!!
 
As for "best practices" for the screen itself - try to get the screen set up about 2-feet beyond the doorway walls - more if you can pull it off - then put lights just outside the doorway walls on each side pointing in on the surface of the screen. Some from above the doorway too if you can. This will give you nice even lighting of the screen - and BOY does that make it easier in post.
 
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