animating shadows in 2d animation

Are we talking cell shading?

A simply method would be using your backlight and animating the shadows on the back of the character's cel, tracing the character's outlines. Then scan both sides, colour the shadow black, flip it and lay it over the character level at whichever degree of opacity you need for the scene. Or you could draw the shadow line directly into the character clean-up and paint it in the colour of the adjacent shadow area.

A simply method would be using your backlight and animating the shadows on the back of the character's cel, tracing the character's outlines. Then scan both sides, colour the shadow black, flip it and lay it over the character level at whichever degree of opacity you need for the scene. Or you could draw the shadow line directly into the character clean-up and paint it in the colour of the adjacent shadow area.

I have heard of a feature on some applications that has an auto drop shadow for the drawings.

Oh, yeah. I was thinking about body shadows, not shadows cast by bodies on their surroudings. I guess if it's a simple, undistorted shadow, like a shadow against a flat wall in a medium shot, you could just copy the character on an underlying layer, fill it black and reduce opacity, maybe blur it a little, depending on the intensity of the light ...

It would be helpful to know what type of medium you are animating in. If it's 3D, which it doesn't sound like, then the computer takes care of most of it for you. For traditional, you'll have to draw most of it.

Finston was sort of right. He's talking about light, point and parallel, but those don't really have too much effect on character shadows in animation.

There are two types of shadows, Cast and Form. A cast shadow happens when an object is between another object and the light source, "casting" a shadow onto the object below. Form shadows are created do to the form curving away from the light source, like the shadow on the underside of a ball. The main difference between the two are the edges of the shadow. A cast shadow has a crisper edge, versus the form shadow that has a more gradated edge to it. Of course there are exceptions and shadows depend on the type of light source and the amount of light sources.

I bring it up because if you're going to have soft edge shadows, you need to put them in the right place. If your animation is a more graphic style and all your shadows are hard edge, then, well, that solves that problem.

If you are going to animate shadows traditionally, rough animate all your characters first and don't even worry about shadows. Once you are happy with the timing and posing in the rough animation, then think about shadows. You can either go on a layer over the rough animation and put in rough shadows to make sure it works right. Then tighten it up when you go to clean-up. Often, traditionally, character animation was in blue, while effects like shadows were drawn in red. But you can use any colors you want. Just stay consistant so you don't get confused and think a shadow line is a shirt line or something.

Shadows are a pain in the butt to animate traditionally and I'd suggest not using them unless you really need them.

Aloha,
the Ape