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weis5on
02-17-2015, 09:47 PM
I recently ran across a video in which someone used a matte node to do a sky replacement in Resolve. The result wasn't bad; but, it got me thinking. I've seen large production films use green screens in backgrounds and on windows to create properly exposed exterior shots. How time consuming of a process is that? Is that typically done in Nuke or After Effects? I have no experience with that work, and I'm genuinely curious. Also, if the window in your scene had no movement across it and the camera was locked down such as in a talking head shot, would that be a much easier process to composite? Under those circumstances could you use Resolve matte node or add alpha matte to replace a blown out window with a shot of the same window stopped down? Seemed like an interesting way to match outside exposure without using a ton of lights or ND window treatment. I tried it in Resolve and it looked pretty bad, but I had never tried it before, so that's not an indication that it can't be done.

Thanks

KurtF
02-17-2015, 11:49 PM
Don't know about the time involved, but here is an interesting behind the scenes on "Gone Girl" which used studio sets and green screens. Mostly for sound, but also for lighting and background control.

http://nofilmschool.com/2014/12/david-fincher-gone-girl-vfx-reel-artemple

Should be doable for most folks, but you've got to have the space, the lighting gear, and the software/skills to track the shot, pull the key, and composite the footage.

Howie Roll
02-18-2015, 12:56 AM
If your goal is creating properly exposed exteriors use ND or more lights inside. If background replacement is your goal this might be an option but you can't simply use a matte to turn a sunny window into nighttime and vice versa. The light coming through the window, or lack thereof, will be a sure tell that it's fake even if the window is replaced. Green screen is an option but you need to be meticulous in planning what is now a VFX shot or shots. You'll spend way more time shooting plates than you would if you used a little ND and that's just production once you move into post you've increased the amount of time involved tenfold.

I've never been overly concerned with what's happening outside the window during a scene unless I need to be, let the highlights blow, if the audience is looking out the window during the middle of a scene you've lost them, at that point who cares what's out there.