How do they make films like 'Who Framed Roger Rabbit', 'Space Jam', etc.

If the scene has the actor in an entirely animated world they have him or her in front of a green screen and the artists add in the backgrounds and characters using cells to overlay the scene.

And with the actors interacting with the cartoon characters, they have them interact with props or pretend to be interacting with someone, they then run the footage frame by frame and have the animators put their animation paper over the scene, draw the characters over the props or where they're supposed to be and have the inkers and painters fill in the color, then they run both scenes through an optical printer which allows people to shoot two strips of film at the same time, then the footage with the animated characters would be shot on a rostrum camera which can be used to film still pictures or objects and make them seem like they're moving, and the effects animators would add in highlights and shadows to make the characters seem more 3 dimensional.

Interesting. This always baffled me. Thank you so more for your in-depth answer, comic_guy87!

Don't be ashamed to scream-it relieves the tension

I'm a huge nerd so I can't help but elaborate on this.

"Who Framed Roger Rabbit" superimposed animated cartoons onto live-action with the use of an extremely sophisticated optical printer that ILM called "the Quad." This photographic technology has since been made obsolete with the advent of digital video.

Say you've got the live-action footage of Eddie Valiant talking to Roger Rabbit. Since this was in the film days, they probably handed the scenes that needed cartoons in them over to the animation department, where they animated the characters the traditional way -- by inking and painting them onto clear acetate "cels," and then photographing them frame-by-frame on a special camera setup.

The way film works is that unlike video, you can't go back and record over what you've already shot. I mean you can, but you'll get a double-exposure. So if you just re-expose the live-action shot of Eddie Valiant onto fresh film stock in the Quad, and then rewind the fresh stock and expose the footage of Roger Rabbit onto that, then you'd see the background of the scene right through Roger Rabbit.

What you need is a third strip of footage called the "male matte" which is a purely black copy of the footage of Roger Rabbit, a silhouette of him. This "male matte" is sandwiched over the live action footage in the Quad (a process called "bipacking") so that its copy on the fresh film stock has a black silhouette of Roger Rabbit.

The fresh stock is rewound and on the next "pass," the animated footage of Roger Rabbit is exposed over that. The cartoon will now appear opaque because the live-action background behind it has been blotted out by the male matte.