The Technology Behind Bullet Time

Special effects come to the rescue of film makers when they want to depict scenes that are unfilmable. Such sequences include bullets flying past the subject, and characters floating in thin air. One such still-frame based technology is known as bullet time. Here’s a quick look on how it works.

A series of still cameras are placed in an arc formation, and all go off simultaneously to capture the subject from various angles. Thus the cameras go off at the point of impact i.e. when the bullets fly, tracing an aerial path in slow motion. Due to the camera positioning, the shot looks like its panning around the subject. The subject is usually suspended on wires and is shot against a chrome screen. These shots are then morphed together and the speed of the scene is set with the help of specialized software. The final background video is then composited with the bullet frame video.

Although Blade (1998) was the first movie to use bullet time, that too in its traditional style, it was the first of the Matrix movies that really made it popular. However, it did not really stick to the conventions. Instead of capturing images simultaneously, the images were captured as a sequence, and the placement of the cameras at varying heights gave the final video a pan and rotate effect. Moreover, since the Wachowski brothers were more into the comic book style of movie making, the sequences of the film reflect an anime look.

Since your subject is shot against a chrome key screen, you can composite the bullet time video with a video of the final surroundings using virtual cinematography software. What you need to keep in mind is that the background video should pan in sync with the bullet time angles. You can use normal pan speed and play around with the panning speed of the bullet time motion as per your requirement in the video compositing software itself.

Bullet time is a visual effects technology that plays around with speed of a particular sequence to generate special effects. The sequence generated is not filmed but is a simulation created using photography. Traditionally, bullet time techniques are based on the same principle as that of stop-motion animations. This technology is not only used in movies, but also in television and video games. Max Payne (2001) was the first game to adopt this technology.