Sadly, it comes with experience, and by experience I mean failure.
When you’re a one-man band, you can’t promise your production everything. Sometimes is cool being hero, the know-it-all, when it comes to sloppy shooting but I’d rather be the strict vfx guy who said “no, you can’t do it that way, take 5 minutes to do it right” than saying “yeah, go for it!”
I have to say this: if you look through the lens and you aren’t happy with the shot, change something on-set. It’s like saying “don’t wipe down that table, we’ll do dust removal in post!” well which takes 30 seconds and which takes 10 minutes?
Another way of thinking about it, is can it be done in Photoshop? If you could relight an entire scene, photographers wouldn’t be buying $20,000 strobe kits. You have to narrow the scope of that understanding a bit further because video complicates things, you’re working with objects that can shift perspective.
When you’re on-set, the biggest piece of advice I can give you is know how the greenscreen process works, independently of any software. You’ll be armed with knowing how to reduce color spill, if a green screen is properly lit even in dark scenes, how and where to place tracking markers. There is about 50 years of keying history and technique to stand on, back to when it was done with analog signals and equipment.
Keying in the most base sense is using the difference in color channels (green vs red and blue) to help create a matte around the subject. There are more optimized ways to key footage than using a single Keylight filter and hoping for the best: You can split the scene up into multiple layers with loosely tracked garbage mattes so you can key different subjects differently, you can use core mattes to key the inside of the subject then use a more subtle key for the edges, or a combination of the two.
Make no mistake, you will have to clean up mostly all green screen shots with some rotoscoping or edge erasing because of high motion blur or other issues.
Angelo Lorenzo
Fallen Empire Digital Production Services – Los Angeles
RED transcoding, on-set DIT, and RED Epic rental services
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