chroma key shadows - what can you get away with?

Naren Wilks · June 23, 2013

Hello, I've been reading various forum posts and articles on chroma keying, but I've gotten a bit stuck on the issue of shadows. I know it's preferable to not have any, but what can you get away with? Below are links to photos of my set, which is a circular room currently painted (badly) white, and lit by 8 fluorescent lights that sit evenly around the top of the circular wall. It's essentially a time-slice / bullet-time setup, with 8 cameras capturing the same action from different viewpoints. I want to paint the whole room with chroma key green to isolate the performer, but I'm worried that the faint shadows cast by the performer will cause me problems. The performer will be wearing a black and white costume.

http://www.flickr.com/photos/narenwilks/9117291805/

http://www.flickr.com/photos/narenwilks/9119513436/

Now I'm assuming that there is some leeway regarding shadows, judging by some of the things I've seen online, most notably this photo of Keanu Reeves on the Matrix set:

http://ralph-dte.eu/files/2011/02/matrix_chroma_key.jpg

But how much leeway? My cameras are stationary, and the lighting is constant. Any help would be great appreciated! Many thanks, Naren http://www.naren.co.uk

Bar Solomon · July 17, 2013

As long as you're not shooting on the scarlet (the worst camera there is for greenscreen)! You can probably pull off a nice key though the spill seems like it might be intense if the talent anywhere but center. I would recommend primate in NUKEx if you run into trouble.

Are you using the 8 cameras over and over again as if to 'fill in the gaps' like you had a full 360 to work with? I did one using a similar method if so.

I will say that if you're doing that, the motion of the talent must be PRECISE every angle change. Otherwise it just doesn't really look right when you try to go all the way around. Unfortunately we had a really poor subject so I ended up just using segments of each angle in it's own time and not doing a "bullet time" kind of thing.

Good luck I'd like to know more info.