green screen - attention wideopenwest

netkoala wrote on 11/23/2003, 2:07 AM
Anybody know of a good portable Green/Blue screen system ?

Seems that constant and even light is needed and no shadow.
So painting muslin cloth a blue or green probably will not work well - so I aint going to try it.
I read that blue is better on skin tone, but found green better in pShop for me ages ago but was hard on blue colour( but no training) . Also read green 4 brunette blue 4 blondes

So it means perhaps painting a wall or using something like http://www.digitaljuice.com/store/flexdrop2.asp 5'x7'

Any kits that can do a larger area ? Say 8'x8' or 8'x9'.

Thought the subject would be good for site www.wideopenwest.com.
Beliieve you can vid the person on screen and then an empty screen.
Supposably this allows you to vary the speed on either. Guess this open up the possibility of more than just a still as the background ???? Not sure anybody know why you would want to vid an empty background ????



Comments

jaegersing wrote on 11/23/2003, 3:52 AM
Spot did a great demo of shooting against green and blue screens in his recent tour to Singapore. (Spot, thanks for the insightful video production seminar - it was wonderful.)

He used a portable screen that was reversible, with blue on one side, green on the other. (I think it was a Photoflex product). Don't know if it comes in the large sizes you need however.

As you say, the lighting on the screen has to be even, and Spot accomplished this using a diffused light at each side. The subject was placed quite a bit away from the screen, and lit separately. The green screen shots I took came out really well, with a very clean key. (As predicted by Spot, the blue screen shots didn't work so well, but it's nothing to do with hair colour.)

Richard Hunter
netkoala wrote on 11/23/2003, 3:55 AM
Okay,
so theoretically i have painted a wall, but now have moved the camera to the side, so only see 1/4 of the green screen.
When I digitally project an image into this area it has to now be scewed and off to the right, to fit the square wall (which is looking unsquare now from this angle).

Can the background be scewed off centre ?
farss wrote on 11/23/2003, 4:51 AM
Why not key the whole thing?
Why have only part of the background as a key color or am I missing something here?

But to answer your question assumig you mean can the background which i bing used for the key be skewed then I can see no reason why not so longas through th camera it is a consistant level, having any fall off across the background being used for the key would seem not a good thing.

BTW have you looked at the relective key material?


It can be quite wrinkled and still work. You make it 'green' with a ring of green LEDs around the camera lens. The screen replects the light back into the camera lens.
netkoala wrote on 11/23/2003, 5:31 AM
People are saying maximise the distance between the green screen and the subject, even back light the subject so as to avoid the hazzle you can sometimes get.

Reflective material and LEDS on the lense sound complicated.

To get even lighting and 180 degree green screen would mean 1/2 a sphere.
This is not possible for me.

Can't always guarantee I will be front on. Limitation to green screens I guess.
If your on a ladder then the angle of your new background would really want to fit stretch or squeeze for the angle. From the top of the ladder the background behind the subject is more likely to be the ground rather than the sunset.

Since skewing the overlay seems hard and lenghty work, ti seems more plausible to get on a ladder, same height and shoot your backdrop later on at the same angle.

i.e. if you capture your subject 45 degrees away from front on, you later go to a building wall and vid that at a 45 degree offset so the background angle should match the angle of the subject from the camera.
Do this even if it is a horizon background.

Means carrying a tape measure and pen and paper.

Simple I suppose , your background fill ought to be at the same angle that your green screen is to the camera.





Chienworks wrote on 11/23/2003, 6:42 AM
Netkoala, i'm not sure if i'm reallly following you or not, but it seems like you're trying to be unnecessarily complicated. I can't think of any reason why the green screen has to be at the same angle as the backgroun you're replacing it with. The idea of the green screen is that it will disappear in the final video, so it doesn't matter where it is or what the angle is. You can always keep your subject centered in the green screen area by moving the subject and/or the camera as necessary. There is no necessity to match the plane of the green screen to the eventual background.

You do want to make sure you shoot your subject from an angle that makes sense with the background. If you want a shot of the subject from a high angle looking down, then you can put the subject up on something as well to make sure that the green screen is still filling the frame behind him.
beerandchips wrote on 11/23/2003, 11:30 AM
As far a portable system. You can buy green or Blue screen cloth kits at proffessional video stores.