The Bullet Time Effect

Ryan Sullivan, Mike Ford, Patrick Johnson -- Spring 2009

What is it?

The Bullet Time Effect is an effect used in film and video games to radically transform time (slow enough to show normally imperceptible and un-filmable events, such as flying bullets) and space (by way of the ability of the camera angle--the audience's point-of-view--to move around the scene at a normal speed while events are slowed) in a scene. Most of you will be familiar with its use in The Matrix Trilogy in scenes such as this one:

History of the Concept & Technology

Perhaps an early ancestor of the Bullet Time Effect were Eadweard Muybridge's sequential photographs of a galloping horse. Muybridge used several still image cameras placed along the racetrack. Strings were attached to each and stretched across the track and a camera would be triggered when the horse ran through its attached string. Muybridge then placed the images on a glass disk and rotated the disk in front of a light source to create a simple animation.

Next up was Doc Edgerton's photos of bullets in the 1940s. Edgerton, a professor at MIT, used a xenon strobe light to "freeze" motion and capture these images.

Bullet Time has also been used in films such as Blade and Wing Commanders, games such as Max Payne, and several television shows and music videos. In fact, it is thought that the opening sequence of the 1960s show Speed Racer partially inspired the Wachowski Brothers to use the effect in The Matrix.

How it's Done

Bullet time or time slicing has a fairly simple concept and can be made by anyone with a few dozen cameras and a little bit of know-how. First it is important to understand that bullet time and slow motion are not the same. Bullet time specially refers to being able to pan around the subject with complete control of time. In an ideal situation, slow motion digital cameras would be used to film and create the bullet time effect but the cost of several dozen of those cameras is not financially freezable for even the largest of budgets.

The first step to building a bullet time filming rig would be acquiring several dozen digital cameras. In the making of a low budget rap video they they used Olympus SP-510 UZ (roughly $299.99 or less) and in another low budget set-up they used Nikon D70's. For the filming of The Matrix they used 120 still film cameras and scanned each image into the computer separately.

After acquiring the cameras they must be arranged in their desired path. In a lower budget settings this is a simple 180 degree path around the subject. This is for two main reasons: the more complicated the path, the more cameras needed and the more post production work required (exponential).

After the desired path is conceived the cameras must be mounted and linked together. Linking the cameras would traditionally be a hazardous step for a home made set-up but thanks to technological advancements, remote USB shutter controls can be found on many low-end digital cameras and this allows multiple cameras to be easily linked. Once everything is in place it is up to the director to click away and collect the raw data. In the home made set up this means that you can shoot until the batteries die or the memory cards fill up on a few dozen cameras. The rig that was used in the filming of The Matrix is estimated to cost $100,000 per day!!!

The final steps are where the home made set-up departs from a professional film studio. In the home made set-up Final Cut Pro is used to simply combine the desired sets of images based upon time. In this scenario the director can not choose much more than to pan right or left at a set speed (based on when the cameras originally were triggered).

The most exciting aspect of The Matrix is that in post production frames can be literally created with perfect accuracy. This is done using interpolation software. The word interpolation refers to a mathematical idea of determining the connecting points in between two points in space. In theory, this means that an infinite amount of frames can be taken from a single set of images using interpolation software. In The Matrix certain scene required near 12,000 frames per second!!! As mentioned in the history of bullet time this effect has been done many times before the filming of The Matrix but this was interpolation software's big daub.

Bullet Time in Art?

On the 3rd of October 2008, Artists in connection with Nexus Productions produced a Time Slice / Bullet Time exhibition in the main foyer of The Tate Britain London. "we produced a system which produced an effect that represents the Francis Bacon painting, "Study after Velázquez's Portrait of Pope Innocent X" in Bullet Time Photography. We used 15 DLSR cameras, wired them up to 2 servers which downloaded the images instantly as the images were being taken, those 2 servers then fed to a shared folder on another computer, which created a new directory on the fly as a each new set of images was taken."

The Future of Filmmaking

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