Chroma Keying
Today
we were introduced to Chroma-keying which is the layering of green screens.
This is done to remove the white fuzz that often appears around actors in front
of a screen, such as on Flash Gordon.
300
was the first film that was filmed completely on green screen, with no location
filming.
To
ensure filming on green looks good you should use Chroma paint, or the correct
blue or green colours. If using material then it should be totally flat with no
creases which can cause shadow, which can also be caused by uneven lighting.
In
a group we attempted to film on Zu3D using basic green. Using a piece of green
felt draped over a flat brown piece of cardboard, we attempted to make the
surface as flat as possible so that we would not have any shadow. However, even
without a character on screen this proved difficult because of the light.
Firstly we was in a room with inconsistent lighting, with 8 room lights, some
on some off which threw the balance off. Secondly there was many people in the
room constantly moving which meant the light was constantly changing. This gave
the light on camera a sort of "jumpy snowing" effect. To counter this
we put a lid on top, thus blanking out the lights from above. As we could not
stop people moving behind we had to ensure that the camera did not move to
create a still as image as possible, whilst positioning ourselves in the same
position for every screen shot. When we thought we had a flat as possible back
we introduced a white horse which didn't blur too much. We then took away the
green background using the Zu3D function which left an almost plane black
background with minimal snowy effect.
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