Green Screen Question.

#1

In a couple of days I am shooting a short movie entirely on green screen. I have completed [mostly] all of my sets/scenes and locations. My plan is to shoot what we need on green screen with a X and Y 0,0 marked on the ground and measure my distance from that as well as my Y height and the angle of the camera to the ground. However, one of my friends brought up a good point… where should I take the measurements from? The front of the lens or from the back of the camera where the lens and photo-recepotors are.

Also, does anyone have any advice on measuring distances and measurements on set so that I can easily set up my cameras in the 3D App and render out for compositing? I have a few ideas in my head but if anyone with real experience on green screening with no budget has info on how to measure angles/distances etc. it would be awesome.

Thanks,

-JIII

#2

i’d like to know also.
Also I wonder how the camera settings in the compositing software should be matched with the reallife camera lens. Anyone got any tips? I’m a newbie and have no idea what field of view and aperture means and how it relates to the reallife lens.

#3

haha, so we shoot in the next 2 days [or don’t shoot at all], so i will make sure to post my results. but it would be awesome if I knew :-).

-JIII

#4

On the last Shooting I worked on I saw the techs getting mesurements from (more or less) the middle of the objective. They told me you have to measure from the reversion point…

I hope it helps and that they did not joke about it, I’m not too good with it.

Hal.

#5

That makes sense. On some professional cameras/Lenses there is actually a mark for this… there was at least on the last two shootings I attended.

As for the size of the lenses / FOV:
make sure you have some way of defining the size of the film/chip. A 20mm lens on a 16mm camera is different to a 20mm on a 35mm camera. Make sure you put in the right values in your 3D app.

-k

#6

Also watch taking very wide-angle shots with lots of lens distortion. As far as I know Brazil and Maxwell will actually simulate a photographic plate as opposed to the standard pinhole-type camera in 3d apps, without this you’ll have to apply some post effects to get similar barrel distortion.

#7

This helped me a while back.

http://www.dvcreators.net/products/dv_enlightenment.html#

Check the top right corner box labeled short video excerpts
and click on the lighting greenscreen box.

the dvd is pretty good itself but the short video pretty much gives you most of what you need. enjoy!

#8

Reversion point? I am not accustomed to film cameras is that the point where the picture crosses over as it goes through the camera and becomes reversed?

Thanks,

-JIII

Sadly, I don’t have time to order a DVD now as we are shooting very soon, a matter of hours to be precise but I will make sure to view it later.

#9

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.