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Chapter 4 : A HISTORY OF COMPUTER ANIMATION 3/20/92 28 motor had penetrated all facets of the movie studio, including camera heads, props, animation stands, optical printers, and ??this true motion control systems . The first computerized animation stands and optical printers were built by John Oxberry, a manufacturer of animation stands and optical benches, and the Atlanta company Cinetron (196?), a startup business . Oxberry's first computerized stands used a DEC PDP-8 computer, Cinetron adopted the Hewlett Packard ???? . In a minimal system (fig . 4-55 .5), a computer and terminal are attached to an animation stand consisting of a compound table and zoom column such as was illustrated in fig . 4-22 . For an optical printer the computerized parameters are the same as those shown in fig . 4-3 .3 . Initially most systems were equipted with paper tape I/O and had no on-line magnetic media ; today a floppy disc drive is standard . The computerization of the stand brings all of its degrees of freedom under formal command-control . These include table X and Y translation, table rotation, the movement of both pegbars, camera vertical movement, frame advance/reverse, and shutter angle . Readouts on the stand, whether they are physical veeder scales or electronic number displays, correspond to the coordinate system of the commands entered by the operator via the keyboard . Such a system may also be used in input mode by positioning the peg bars, compounds, and camera and capturing all the counter values into computer memory . The operation of the camera and the positioning of the components may also be done manually using hand cranks or via the computer using a joystick . To photograph a sequence the operator composes a series of commands, possibly incorporating some of these saved data positions, which the computer interprets and outputs as a sequence of stepping increments which are sent down the bus to an I/O port where they are translated into electrical pulses which turn the motors and shoot the sequence of frames . In fact the actions may even be previewed before actually shooting film . Benefits of Computer Animation Stand The computerization of simple animation and optical effects equipment expanded the productivity of the cameraman . One one hand it made the job easier . Human error was still a factor, only 55 .5 Computer controlled animation stand . Commands entered on the keyboard and displayed on the screen orchestrate stepping motors on the stand to replicate the actions of the cameraman .
Chapter 4: A HISTORY OF COMPUTER ANIMATION 3/20/92 29 now once the cause of a flaw was discovered it could be repaired without another error slipping in somewhere else during the reshoot . But on the other hand the job became more complicated, because the sequences of action themselves became more complicated . One could shoot tests easier, encouraging more previewing and fine tuning . Moves which would before would have been troublesome or impractable were now the orders of the day . Above and beyond automating the animation stand or camera rig it quickly became obvious that the computer conferred some new and unique benefits to the animation process . One of these benefits was that a new kind of scripting language emerged which addressed the photographic process as a series of linear commands, rather than the spread sheet style of the exposure sheet . Because we discuss languages in more detail later, we defer further development of this topic here . Another immediate benefit was that the computer could perform calculations, particularly eases, fades, and dissolves . Motions could now be defined only by their extreme positions, and the CPU could calculate the intermediate positions for pans, tilts, rotations, zooms, and traveling pegbar, and position the mechanics accordingly . Fades of any length (and not only the classically prefigured lengths) became trivial because of the precise shutter control . Precise shuttle control (frame advance) made skip framing, double frames, and holds easier . The filming of cyclic action became simplified because the computer could quickly and reliably open and close the shutter in coordination with frame advance . For example an eight cell cycle could be filmed with only eight cel changes-the computer simply ordered the first cel mounted and shot every eighth frame, then rewound the camera and ordered the second cel mounted . This reduced handling dramatically and extended cel life . The use of a computerized animation stand in input mode, that is to site thru the camera viewfinder or project a field guide and then capturing the numerical positions of N-S, E-W, and zoom into memory, provided an ability to digitize control points, camera and table positions that are obtained empirically . This provided the fielding director an alternative to keyboarding positions . After a series of control points is captured the computer may be instructed to move from one to another according to some (easing) rule in some number of frames . Or, the compound table might be instructed to move from one fielding to another along the path of an arc . A variant idea is to assign frame times to a sequence of control points and construct a spline through them . Or a freehand path may be drawn,
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Chapter 4: A HISTORY OF COMPUTER ANIMATION ... - Vasulka.org

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