Published : 21st November 2005
I once worked on a TV show where we used puppeteers clothed in a green material with a green LED ring lite around the camera. When walking by the camera's axis, the green material on the puppeteers "came alive". For the most part we keyed the puppeteers easily, but not always perfectly. I'm GUESSING that we probably used 3M's Scotchlite material.
I gather a company named Reflecmedia makes a product named Chromatte. This is a grey material that takes on the colour cast of the LED ring lite used to light it (blue or green).
Does anyone know which material is best used with this kind of LED ring lite system? This would be for a stage shoot in HD under tungsten lighting conditions. The "material" to be keyed would be mounted as "windows" on vertical panels which will need to rotate completely away from camera in shot, keying throughout their entire rotation.
Gaffer / New York City
>rotate completely away from camera in shot, keying throughout their >entire rotation.
This is exactly what Reflecmedia claim for their system - that it has better off-axis reflection ability than standard retroreflective materials and can be used fairly well folded-up.
That said I don't think they ever claimed that it was perfect through 180 degrees and from what I have seen of it, when you have ripples and folds in the material and some part of it is at some harsh angle to the camera, the return is pretty attenuated.
This might not be disastrous as it doesn't affect the saturation, but there will obviously come a point where it becomes unacceptably noisy. On the other hand I have also seen it used on a virtual set type environment where things were just draped with it, obviously including folds, and that seemed to work OK.
Just bear in mind that the version I tested of this, a long time ago, at the BBC, where it was developed, had problems with high resolution systems.
Specifically with 35mm, it would show a banding in the screen.
Geoff Boyle FBKS
Director of Photography
> it would show a banding in the screen.
Yes, seen this - you get a ring of slightly brighter blue, it's visible with the naked eye if you look through the ring. Presumably the same phenomenon that creates rainbows and those rings around the sun on rainy days (which are also circular, if only the horizon wasn't in the way) with the tiny glass beads standing in for the drops of water. There will be a name for this phenomenon which I... can't remember.
Since it doesn't affect the saturation, only the brightness, it shouldn't be too much of an issue.
> Does anyone know which material is best used with this kind of LED >ring lite system?
Is this for a live switched production or something that will be finished in a post production operation.
If it will have the keying done in post then it should not be a big deal for the VFX folks to track the window for a couple of frames. With flat, regular shaped objects like windows it makes the job rather easy.
This may be a case where a little honest communication with the post folks could save a lot of hassle on the set. I've seen many folks go to a lot of trouble to get that last bit of perfection, just to find out it did not need to be totally perfect.
Industrial Magician (and boat anchor mechanic)
Marty Brenneis wrote:
>Is this for a live switched production or something that will be >finished >in a post production operation.
It will be finished in post production.
Gaffer / New York City