User:Father Goose/timeslice

Timeslice (or time slice, also known as bullet time, frozen time, time freeze, and timetrack) is a visual special effect in which variable speed photography (slow motion, time-lapse, freeze frame, etc.) is combined with a moving viewpoint to simulate dynamic movement through a slowed or frozen film shot, or to portray normally imperceptible high-speed events, such as flying bullets.

As an optical filming technique, it is accomplished by the use of multiple synchronized still cameras; a single shot from each camera is used in a single frame of a moving picture to create the illusion of a single camera moving through a slowed or stopped landscape.

Timeslice is distinct from regular slow motion, in which camera movement (if any) is also slowed (in proportion to the slowing of the film). It is also distinct from the narrative device of stopped time, in which a character moves through a "frozen" landscape due to time being stopped (or due to the character's movements being sped to the point where other objects stand still, or nearly so). Howver, timeslice effects may be used to simulate stopped time.

Technology

As an optical filming technique, timeslice is accomplished by the use of multiple synchronized still cameras surrounding a subject.

a single shot from each camera is used in a single frame of a moving picture to create the illusion of a single camera moving through a slowed or stopped landscape. Additional interpolated frames may be inserted between the photographic frames to smooth the simulated motion.

was originally achieved photographically by a set of still cameras surrounding the subject. These arrays can be triggered at the same time, or a linear sequence. Single frames taken from each of the still cameras are then arranged and displayed consecutively to produce an orbiting viewpoint of an action frozen in time or as hyper-slow-motion. This technique suggests the limitless perspectives and variable frame rates possible with a virtual camera. However, if the still array process is done with real cameras, it is often limited to assigned paths.

In The Matrix, the camera path was pre-designed using computer-generated visualizations as a guide. Cameras were arranged, behind a green or blue screen, on a track and aligned through a laser targeting system, forming a complex curve through space. The cameras were then triggered at extremely close intervals, so the action continued to unfold, in extreme slow-motion, while the viewpoint moved. Additionally, the individual frames were scanned for computer processing. Using sophisticated interpolation software, extra frames could be inserted to slow down the action further and improve the fluidity of the movement (especially the frame rate of the images); frames could also be dropped to speed up the action. This approach provides greater flexibility than a purely photographic one.

An effect equivalent to timeslice can also be rendered directly using 3D computer graphics.

History

As an optical technique, timeslice was commercialized in 1996 by Dayton Taylor (who called it "timetrack") and used in several television commercials. The technique was popularized under the name "bullet time" by the Wachowski brothers, who used it extensively in The Matrix series of films, starting in 1999.

Long before the emergence of a technology permitting a live-action application, visual sequences similar to the timeslice technique were featured in cel animation. One of the earliest examples is the shot at the end of the title sequence for the late-1960s Japanese anime series Speed Racer: as Speed leaps from the Mach Five, he freezes in mid-jump and the camera does an arc shot from front to side view.

Although the movie Blade, made in 1998, incorporated bullet-dodging scenes similar to the "bullet time" sequences in The Matrix, these scenes did not use timeslice techniques; the bullets were computer-generated and digitally implemented.

Antecedents

Muybridge horse photos

Antecedents to timeslice occurred before the invention of cinema itself. Eadweard Muybridge used still cameras placed along a racetrack to take pictures of a galloping horse. Each camera was actuated by a taut string stretched across the track; as the horse galloped past, the camera shutters snapped, taking one frame at a time. (The original intent was to settle a debate the governor of California had engaged in, as to whether all four of the animal's legs would leave the ground when galloping.) Muybridge later assembled the pictures into a rudimentary animation, by placing them on a glass disk which he spun in front of a light source. His zoopraxiscope may have been an inspiration for Thomas Edison to explore the idea of motion pictures. (Hendricks 1961)

Muybridge also took photos of actions from many angles at the same instant in time, to study how the human body went up stairs, for example. This is the effect used in The Matrix, and other movies, and is achieved roughly the same way as Muybridge set up his shots. In effect, however, Muybridge had achieved the aesthetic opposite to The Matrix's bullet-time sequences, since his studies lacked the dimensionality of the later developments. A debt may also be owed to MIT professor Doc Edgerton, who, in the 1940s, captured now-iconic photos of bullets using xenon strobe lights to "freeze" motion.

John Woo is also famous for incorporating slow motion shoot outs in his movies, such as A Better Tomorrow and Hard Boiled. These films would later influence media such as Max Payne and The Matrix series.

The first music video to use bullet-time was "Army of Me", a 1995 Björk video directed by Michel Gondry. It was also featured in Dario Argento's 1996 horror movie The Stendhal Syndrome (CGI, with a bullet), and the 1998 BBC documentary mini-series Intimate Universe: The Human Body with time-slice by Tim Macmillan. In 1994, Dayton Taylor invented a film-based system called TimeTrack that was used in many television commercials. Bullet time became popularized when John Gaeta and team expanded it temporally and into the digital arena through the incorporation of frame interpolation and image based CGI within the film The Matrix (1999) and through view-morphing techniques pioneered by BUF Compagnie in music videos by Michel Gondry and commercials for, among others, The Gap.

In 2003, Bullet Time evolved further through The Matrix Reloaded and The Matrix Revolutions with the introduction of high-definition computer-generated approaches like virtual cinematography and universal capture. Virtual elements within the Matrix Trilogy utilized state-of-the-art image-based computer rendering techniques pioneered in Paul Debevec's 1997 film and custom evolved for the Matrix by George Borshukov, an early collaborator of Debevec.

Other applications of the concept

• Speed Racer, 1967-1968. Opening sequence.
• Videoclip for Suede "The Wild Ones", 1994. Dir. Howard Greenhalgh.
• Videoclip for Bjork "Army of Me", 1995. Dir. Michel Gondry.

• Videoclip for The Rolling Stones "Like a Rolling Stone", 1995. Dir. Michel Gondry.
• Videoclip for Sting "Let Your Soul Be Your Pilot", 1996. Dir. Emmanual Carlier.
• Videoclip for Smoke City "Underwater Love", 1996. Dir. Tim MacMillan
• "Little Bitty" Alan Jackson video 1996.
• Videoclip for Coolio "C U When U Get There", 1996.
• Video for Meat Beat Manifesto's "Helter Skelter '97", 1997, directed by Ben Stokes
• "Landscape", 1997. This short computer animation by Tamás Waliczky won a prize at the 1998 Prix Ars Electronica cyberarts competition.
• Videoclip for Van Halen "Without You", 1998
• Videoclip for Garbage "Push it", 1998
• The movie Lost in Space (1998) features a scene similar to bullet-time: When ship enters hyperspace, all the action freezes, but the point of view moves slightly in an arc.
• The music video for the song "Guilty Conscience" (from The Slim Shady LP) features Dr. Dre and Eminem speaking as good and evil consciences to three different men frozen in Bullet Time.
• The film Wing Commander (1999) performed poorly at the box office, though the trailer gained some notice for its inclusion of the film's bullet-time scene, showing people, and a spilling cup of liquid, captured in mid-air.
• Videoclip for Meat Beat Manifesto and title sequence for Howard Stern's televised radio program, both directed by Ben Stokes of the influential film/video/design consortium H-Gun
• Videoclip for Korn "Freak On A Leash", 1998.
• In Super Bowl XXXV, CBS employed a system of cameras that allowed for bullet-time-like effects on its broadcast. This system proved to be the difference in upholding a replay challenge on a Jamal Lewis fourth quarter touchdown by showing that he clearly broke the plane of the end zone. The Bullet Time was accomplished using cameras only, without any computer interpolating.
• In the opening sequence of the IMAX documentary Michael Jordan to the Max, Michael Jordan executes a slam dunk in bullet-time while practicing at the United Center.
• An episode of the animated series Futurama ("Three Hundred Big Boys") features a scene in which Fry enters a state of hyperspeed after consuming one hundred cups of coffee. In this state, he is able to observe individual wingbeats of a hummingbird.
• Select episodes of the TV series Angel following Season 3's "Home" (3x21) have featured stylized bullet-time action sequences.

References

• Hendricks, Gordon (1961), The Edison Motion Picture Myth, Berkeley, California: University of California Press.

External links

• Bullet Time walk thru, Computer Graphics Overview, Department of Computer Science, Australian National University. Includes Quicktime videos.
• TimeFreezeWiki (German)