The 180-degree Rule

In film making, the 180-degree rule is an imaginary line regarding the on-screen spatial relationship between a character and another character or object within a scene. It allows the audience to clearly understand the sequence and where characters or objects are in relation to each other. As long as the film maker to keep within the 180 degrees. It is often used it conversation sequences.

However there is only one way that a camera can cross onto the other side of the line of action. This if you film the camera crossing the line by the use of crabbing or tracking. Or it can be used to unsettle the spectator.

Here is an example of breaking the 180 degree rule, from The Shining - (Stanley Kubrick 1980), It is used to create an eery uneasy feel.