Hello, i'm testing around some in after effects and i've stumpled upon something i can't figure out, or even if its possible.
I wonder if it’s possible to remove the background behind the blue screen, and just have the blue paper which the man is standing on, as the background for the entire scene. Also, would it be possible to place 2 characters besides each other? (I have footage of 2 different characters with the same blue background)
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Removing the blue background is nothing more than keying. AE has several keyers under the Effects>Keying category. In your shot you would start with a garbage matte easily drawn with a mask and then add Effects>Keying>Keylight.
If you were the one shooting this scene I would suggest that in the future you reduce the amount of light on the blue screen by about 50%. Your screen should be about 1 stop darker than the skin tones. You'll get a better result with less work.
To learn how to use Keylight go to the Search Help menu at the top right corner of AE and type in Keylight and you will find some excellent training materials. To learn how to draw a mask do the same thing, type mask in the search help field. Your project would look something like this:
After Effects is a very complex program with literally millions of possible combinations of effects. The UI can be confusing. If you are just starting out please spend some time learning the basics. A couple of hours spent on Basic AE will save you days of fooling around.
To answer your second question, to put two people next to each other you just use two layers. Compositing in AE is just like cutting out paper dolls and arranging them on a background. The magic is in the layers.
After Effects is for creating shots, not editing movies. Especially when you start out you should limit your After Effects compositions to one shot, render that composition, then do your editing in a NLE like Premiere Pro.
One last minor point. The easiest way to show us what you are doing is to simply drag images or screenshots to the reply field on this forum. If you are on a Windows machine you can use Print Screen and just paste (Ctrl/Cmnd + v) to show us a screenshot.