180 Degree rule

While filming our thriller opening we had to bear in mind the 180 degree rule.  

 

In filmmaking the 180 degree rule is something which needs to be followed. It says that two characters in the same scene need to always have the same left/right relationship to each other. If the camera goes over the imaginary axis connecting the two characters, it is called the crossing line. The new shot which is from the opposite side is called a reverse angle. If the rule is not followed, it may result in the scene looking as if the characters have switched places.  The rule allows the audience to connect visually with the unseen movement happening behind and around the subject and it is important in the narration of battle scenes.  
In professional productions, the 180 degree rule is a important element for a film style called continuity editing. However the rule is not always obeyed, sometimes a film maker may break the line of action purposely to create disorientation.