Frame-by-frame shooting was one of the three major special effects processes used in the making of Metropolis. Traditional animation techqniues were employed throughout the film to achieve effects not otherwise possible for the time. Some of the electrical charges in the heart machine and in Rotwang’s lab are both examples of traditional animation, as are a number of brief sequences in between shots for emotive effect for depicting explosions or bursts. Additionally, the film’s abstract title sequence was animated, depicting lines and surfaces in an art deco fashion. Stop-motion animation was employed for filming shots of traffic moving on the suspended roadways in the city, using a total of three hundred tiny model cars, each of which had to be moved forwards a few milimeters for each frame.