With the help of DHTML we can show you two different strategies animators use.

figure a

Above you see two images, one is a background picture of a hallway that doesn't move, the other the shoulders and head of a person. If you click and hold on the person with your left mouse button you can slide the image over onto the background. Line up the bottom of the person with the bottom of the background. If you look at the image now it looks like a person standing in a hallway. But now if you click on the image of the person and move it slightly up and down it begins too look like they are walking in the hallway. If frames were made of the movement it might look something like figure a.

To cut corners some animators will reuse a single cel and just change it's placement on various different backgrounds in order to simulate movement. Or in some cases create a series of cels and reuse them in a cycle. [Like to simulate walking.] In a similar way a background artist can create one long background, and then only the different cels have to be redone and their placement can be moved on the background and a new background doesn't have to be made. [If you've ever seen animated chase in a hallway you've probably seen this technique used.] Below you can make the ball roll throughout the hallway and see how the technique can be useful.









Below is an animated image that shows how the long background can be used repeatedly.