Rotoscoping
Very detailed rotoscope podcast from Effects Corner part 1
Very detailed rotoscope podcast from Effects Corner part 2
Bill O'Neil tutorial on rotoscoping using vector paint
Pete O'Connell video tutorial on rotoscoping with a moving shot
The Effects Corner tutorial part 2 is very good and exactly what we're doing translated to After Effects.
If the camera is not moving the masking of still-elements should be fairly easy but if there is a moving character in front of the CG elements there is, as far as I know, no other way than to use rotoscoping.
The key point to manage and get a nice roto result is to split the subject up using several masks. The number of masks depends on the shot but for this I decided to do: Head, body, left arm, right arm, left leg, right leg. Start by keying the mask at the key frames (like in animation) by scaling and rotating the mask.Try not to change the overall shape of the mask too much because too many key frames and movement of mask points creates the familiar jitter effect. Again, Effect Corners tutorial part 2 explains everything better than me :)
Also remember to adjust the edges, add shadow and other lighting effect to the masked out layer to make it blend in.
So there we go. I guess that's it more or less. If there are any questions or comments please give me a shout and I'll get back to you.
Again, here's my final with some added effects. (The Pepsi poster is motion tracked and put on in post as well..but required a lot of tweaking...)
