Shooting for the composite
I am shooting a short film with a few compositing shots. I’m shooting on 35mm and then transferring HD. This is my first experience with compositing so I have many questions. The image to be composited is linked below, it was done in photoshop to get an idea of what the film will look like
The plate is the man and the background, the elements to be composited in are the woman on top of the tower and the tower itself. Eventually the man stands next to the base of the tower so that they are both in the distance. And then finally he is on top of the tower with the woman. Here are my questions;
1. When the man stands near the base of the tower should he be green screened and place out there in compositing? This way his scale can be controlled.
2. When shooting the actors in front of a green screen to place them on top of the tower how do I match the angle? Obviously I cannot get a person high enough to match the angle. Any recommendations here?
3. When filming the actors should I fill the frame as much as possible, or get them as close to the right scale as possible? I imagine I could place the green screen on a hill and shoot up. In the still photograph I placed the actress on a table and shot from beneath fairly close up.
These are probably enough for now to get the conversation rolling.
I'm not an expert, but I've shot a fair amount of green screen. I'm assuming you know the technical needs of shooting on green. If not there's a lot of discussion of that you can here on the Cow. Here are some thoughts. 1) Shoot talent full length and with the body orientation you want when placed in the composite. There are a number of ways to monitor your shoot (if you use a video tap on the film cam) so you can see a rough composite in real or near-real time. 2) I'd do the best you can to get the talent up high with respect to the camera. You might be able to exaggerate their position in the composite software. 3)As above, shoot talent full-length and scale them in the composite program. Using green screen out-of-doors will be quite problematic as the sun constantly moves (and there are clouds) causing a varying green on the screen. It would make pulling the key very difficult, perhaps impossible. Hope this helps.
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More pixels=better for keying, always. You can shoot them near the camera, but full-screen/full-body, then the keyed composite of their bodies will look better and better as it gets scaled down to fit the scale of the eventual comp. Your question on scaling while shooting wasn't stupid, just anachronistic; because in the days of live-composited effects shots done with an optical printer, matte paintings and/or gag lenses live on-set, you *did* try to match up your final scales in the initial, basic shot. But you don't need to do that now, for digital. Indeed, doing that now means many fewer pixels to make the shot from, making the job harder, not easier. Bigger image, scaled down, always looks better than small image scaled UP.
Your link didn't work for me, blocked for some reason, so I can't see the sample image, but as far as shooting angles to match perspective, remember, in green screen world, moving the camera and moving the person can be the same thing. Meaning, you could stand your people on a loading dock, then put the camera down low and shoot up at them, and get a reasonable perspective shot, then scale it to suit, and even add a little more warping to enhance the effect you want. You don't *need* to put people up high in snorkel trucks for this... Heck, you could even shoot down into a (first surface) mirror placed on the floor... or you could do like Orson Welles, and have guys jackhammer a camera pit into a concrete studio floor to get just the right low-angle:-)
Drop by the video store tonight and rent the "Spy Kids" movies on DVD; Roberto Rodroguez does some neat mini-tutorials behind the scenes segments on how he did his green screens, and I think this could help you visualize a setup for your needs. The tutorials might also be on youtube by now.
I think if you don't have adequate lighting, you can greenscreen using Mister Sun. It just complicates matters to angle the BG to catch the sun evenly, (which usually needs a bigger backdrop) and not be affected by wind or clouds plus also be far back enough not to catch actor shadows. Then you need to move the entire setup every ten minutes to track the sun. And you want to shoot at a time of day that matches the sun angles of the final shot, otherwise the shadows on the actors will fall "wrong", compared to the back plate, and the effect loses veracity.
This is not a solution or suggestion but just a fun note. Years ago, in the SD days, we actually did a couple "blue"screen exteriors by using the blue sky itself as the blue screen on some low angle shots. It actually worked out.