Techniques of filming using special effects have existed since the 1920's, well before the advent of computers. Two of them are known as Back Projection - when an actor acts in front of a screen that reproduces other footage (very common in train scenes), and Blue Screen -  when an actor acts in front of a blue wall for later composition with another scene. However, it was computer graphics and the computer's advance that made possible great evolution in this area. This work approaches Virtual Sets, describing its conceptualization, and showing its correlation with other areas in computer graphics.
The virtual sets' pertinent technologies are identified in computer graphics 
 and have their given solutions and unsolved problems argued.
Amongst the presented problems, the work studies one technique based on differential otimization aiming at the synchronism of camera that would allow interaction, in real time, of the real and synthetic images.