Zoetrope workshop readme

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Pre-cinematic animation devices

History

Animation - as we might understand it as a technical process of synthesising motion from a series of static images - precedes the invention of the cinematograph by several decades. It has its roots in the numerous game toys / devices, popular in the early 1800s which experimented with persistence of vision effect known as the Phi phenomenon.

Thaumatrope / 1824

The Thaumatrope is accredited to different people. The story takes us back to the early 19 century. On a dinner table with many prominent names, exciting times of discovery and challenge. In his 1864 memoirs Babbage ( mathematician) tells of a dinner party where Herschel ( astrologist) asks those present how he can show two sides of a shilling at the same moment; Babbage's solution: by looking at its reflection in a mirror. Herschel betters this, by spinning the coin. On being told this story, Dr. Fitton (geologist) later brings a painted thaumatrope he has made, to show Babbage.


Traumatrope.jpg

However it is known that Dr. Paris ( a physician, who turned out to be also a good entrepreneur) used his device to show the Phi phenomenon to the Royal College of Physicians in 1824. 'Trope' comes from the Greek word for 'things that turn'. 'Thauma' means wondrous, therefore a thaumatrope is a 'turning marvel' or 'wonder turner'.


LINKS - - - - - >

how it works

A solar powered thaumatrope

Phenakistoscope and Stroboscope / 1832

In 1832 Joseph Plateau (Ghent, Belgium) coined his invention - the phenakistoscope (Greek for 'deceptive view'). That same year, professor Simon Ritter von Stampfer of the Polytechnical Institute (Vienna, Austria) developed the Stampfer Disc (also called the Stroboskopische Sheiben, Stroboscope Discs, optical magic disc, or simply Stroboscope ). Essentially, this was the same device as Plateau's phenakistoscope. These devices were also known under other names such as: Fantascope, Phantamascope, Magic Disc or Kaleidorama.

The simplest phenakistoscope is a spinning disc mounted vertically on a handle. Arranged around the circumference of the disc is a series of equidistant radial slots (usually between 8 and 20), and on the face of the disc a series of pictures representing phases of movement of objects, people or animals. The user spins the disc and looks through the moving slots at the sequence reflected in a mirror, the rapid succession of pictures having the appearance of a moving image. The discs were sold in sets, and could be attached and removed from the handle by a simple fixture.

Phenakistiscopemirror.jpg

Phenac ackermann wood box.jpg

A later version, which eliminated the need for a mirror, had two discs fixed at a distance on the same axis, one with slots and the other (changeable) with pictures. Some sets were designed as table models on wooden stands, with a handle to drive the discs by pulleys.

Phen3.jpg

a video

Zoetrope / 1834

The Zoetrope was invented by William George Horner in 1834. He named his device Daedalum or 'wheel of the devil'. This optical toy was forgotten for about 30 years until it was discovered and almost simultaneously patented in 1867 by William F. Lincoln, USA and in England by Milton Bradley. It was from Lincoln that the device received its new name Zoetrope, meaning 'wheel of life' from the Greek word 'zoo' for animal life and 'trope' for 'things that turn'.

Horner's Zoetrope was an adaptation of the principles of the Phenakistoscope. However it was more convenient than Plateau and Stampfer's inventions in that it eliminated the need for a mirror and allowed several people to view the motion at one time. It was constructed of an open-top drum into which was placed a hand drawn sequence of pictures on a strip of paper facing inwards. The outside of the drum had slits cut into the cylindrical surface. When the drum was spun on a central axis, the images could be viewed through the slits giving rise to the illusion of movement.

Zoetropes 1.jpg

67Marey 300737 Zoetrope.jpg

a short video, always better than words

Kineograph (flipbook) / 1868


The first flip book appeared in September, 1868, when it was patented by John Barnes Linnett under the name kineograph ("moving picture"). They were the first form of animation to employ a linear sequence of images rather than circular (as in the older phenakistoscope).


Kineograph-1868.jpeg

a vid

Praxinoscope / 1877

In 1877, Frenchman Charles Émile Reynaud, refined the principle of the Zoetrope to use reflected light creating the Praxinoscope (patented December 1877). This was the first device to overcome the blurred distortion caused by viewing through narrow fast moving slots and it quickly replaced the Zoetrope in popularity. Like the Zoetrope, a paper strip of pictures is placed inside a shallow outer cylinder, so that each picture is reflected by the inner set of mirrors. The number of mirror facets equaled the number of pictures on the paper strip. When the outer cylinder rotates, the quick succession of images reflected in the mirrors gives the illusion of movement. This produced a image that was more brilliant and sharper than with any previous device.
Reynaud managed to adapt the principle behind his Praxinoscope to project a series of pictures onto a screen. 1892 in Paris, he opened the 'Theatre Optique' - the very first moving pictures shown publicly via projection onto a screen.


Authentic-Praxinoscope.jpg Praxinoscope2.jpg
video that shows it:)

and now a useful image to get the difference :)

Praxinoscope-zoetrope.jpg

Zoopraxiscope / 1879


The zoopraxiscope is an early device for displaying motion pictures. Created by photographic pioneer Eadweard Muybridge in 1879, it may be considered the first movie projector. The zoopraxiscope projected images from rotating glass disks in rapid succession to give the impression of motion.


What Muybridge did was to borrow the animated illusion of movement from moving image toys and combine this with the capacity for projection embodied in the magic lantern. He then adapted pictures from his motion photography and created a device which for the first time could project sequences of rapid movement informed by the camera onto a screen. To many theorists, the Zoöpraxiscope therefore represents a pivotal moment in the history of the moving image - a missing link between slide projection and cinema.


Zoopraxiscope.jpeg


Electrotachyscope / 1899


The electrotachyscope is an 1887 invention of Ottomar Anschütz of Germany which presents the illusion of motion with transparent serial photographs, chronophotographs, arranged on a spinning wheel of fortune or mandala-like glass disc, significant as a technological development in the history of cinema.

A Geissler tube was used to flash light through the transparencies to provide a weak projection to a single person or small audience through a small window.

Electrotachyscope1.jpeg

artist remake

Technology

In short, in order to experience static images as an animated sequence, they must be viewed in a rapid succession and there must be a break of the viewing of the images. In the case of the early animation devices, the images were seen trough a slit, that revealed the image for a brief moment and then there was a break before seeing the next one. This we can call the shutter.

There are other ways to create the shutter, and allow for the animation to be observed.

We will look into two:

  • using a camera's framerate
  • using strobe light (light flashing with a high frequency)

There is also the factor of how long the images are exposed to the viewer. That determines the motion blur, or how sharp do we see the image. That will be the shutter speed at which the camera films in the first case
And will be the fraction of a second at which the light is on in the case of the strobe

Understanding the relationship of these factors- check 2.1 Strobe light + sync


Recent projects

Some very few works that employ the same principles

Tim Wheatley Tim Wheatley is an animator, thus the projects is only seen trough camera

Gregory Barsamian quite amazing sculptural, stroboscopic works. His website design is almost as dazzling:)

Julien Maire a 3d printed film

Scott Blake 9/11 Zoetrope by the artist

Bill Brandt Msstransiscope - Public space artwork

Troika digital zoetrope

Quinten Swagerman Pristitrope

Takeshi Murata sculptural, stroboscopic optical illusion / with flawless documentation

Peter Hudson huge scale 3d zoetropes at Burning man - this is the man

Disney's toy story 3d zoetrope

A music video using praxinoscopes

Sculpture describe themselves as an Opto-musical agglomerate

Sculpture set

Interaction Station Zoetrope teststation

During the first Zoetrope Open Aanbod we built two test stations. They are available in the Interaction station to test animations and make prototypes.
Instructions and documentation to follow here------>
Zoetr.jpg

Potentially useful re-creative technology

Strobe Light + Sync

or stroboscopic light very simply put is a light source that lights on and off very fast. Hope none of us suffers from being exposed at strobing light, as you will probably use it for your projects to be your shutter.


So to shortly wrap it up, persistence of vision is a stroboscopic effect. The images you see must be interrupted by moments of darkness in order for the illusion to work. That is how the phenakistoscope and zoetrope's slits work. The same is achieved with separate mirrors in the case of the praxinoscope.

So there are three factors that we must take into consideration when building an animation device that works with the same principles.

1. Number of frames of animation 2. Frequency of the strobe or Frames per second (fps) 3. Rotations per second of the device (speed)


With the devices, that have slits to create the stroboscopic effect, there is no problem with synchronization, since the faster you turn the faster the slits move. And since they are the same number as the images and placed always so that you see the opposite image, the animation is always in sync.

But when there is a light source or camera frame rate that creates the gaps in between the frames, then there is a formula to calculate the relationship.


The Rotations per second  x number of frames of animation = Frequency of the strobe or camera fps

and then by knowing two of the three factors, you can calculate the other

A good example to understand this is understanding the turntable (record player animation) So there 2 factors are present
1. the speed of the record player - that is 45 RPM (rotations per minute), which is 45rpm/60=0.75 RPS rotations per second

2. the fps of a camera is 24 fps


so according to the formula

0.75 x frames of animation = 24
or frames of animation = 24/0.75 ----> frames of animation = 32



Another factor that plays a role is the actual raction of the second that the light is on in the case of the strobe, or the shutter speed, when using a camera.
of course, that is a mathematical formula that gives you a very good orientation but it is best to adjust the strobe according to the images, while actually looking at it.


Motors

!!! WATCH THIS / very nice video from the Prelinger Archives

DC motors


DC (Direct Current) motors are two wire (power & ground), continuous rotation motors. When you supply power, a DC motor will start spinning until that power is removed. Most DC motors run at a high RPM (revolutions per minute).

The speed of DC motors is controlled using pulse width modulation (PWM), a technique of rapidly pulsing the power on and off. The percentage of time spent cycling the on/off ratio determines the speed of the motor, e.g. if the power is cycled at 50% (half on, half off), then the motor will spin at half the speed of 100% (fully on). Each pulse is so rapid that the motor appears to be continuously spinning with no stuttering!

DC-motor.jpg Dcinside.jpg

servo motors


Servo motors are basically more flavored Dc motors.
They are generally an assembly of four things: a DC motor, a gearing set, a control circuit and a position-sensor (usually a potentiometer).

The position of servo motors can be controlled more precisely than those of standard DC motors, and they usually have three wires (power, ground & control). Power to servo motors is constantly applied, with the servo control circuit regulating the draw to drive the motor.

Servo motors do not rotate freely like a standard DC motor. Instead the angle of rotation is limited to 180 Degrees back and forth. Servo motors receive a control signal that represents an output position and applies power to the DC motor until the shaft turns to the correct position, determined by the position sensor.

PWM is used for the control signal of servo motors. However, unlike DC motors it’s the duration of the positive pulse that determines the position, rather than speed, of the servo shaft. A neutral pulse value depending on the servo (usually around 1.5ms) keeps the servo shaft in the center position. Increasing that pulse value will make the servo turn clockwise, and a shorter pulse will turn the shaft anticlockwise. The servo control pulse is usually repeated every 20 milliseconds, essentially telling the servo where to go, even if that means remaining in the same position.

Servo.jpg Servoinside.jpg

stepper motors

A stepper motor is essentially a servo motor that uses a different method of motorization. Where a servo motor uses a continuous rotation DC motor and integrated controller circuit, stepper motors use multiple toothed electromagnets arranged around a central gear to define position.

Stepper motors require an external control circuit or micro controller (for instance a Raspberry Pi or Arduino) to individually energize each electromagnet and make the motor shaft turn. When electromagnet ‘A’ is powered it attracts the gear’s teeth and aligns them, slightly offset from the next electromagnet ‘B’. When ‘A’ is switch off, and ‘B’ switched on, the gear rotates slightly to align with ‘B’, and so on around the circle, with each electromagnet around the gear energizing and de-energizing in turn to create rotation. Each rotation from one electromagnet to the next is called a "step", and thus the motor can be turned by precise predefined step angles through a full 360 Degree rotation.

Stepper motors are available in two varieties; unipolar or bipolar. Bipolar motors are the strongest type of stepper motor and usually have four or eight leads. They have two sets of electromagnetic coils internally, and stepping is achieved by changing the direction of current within those coils. Unipolar motors, identifiable by having 5,6 or even 8 wires, also have two coils, but each one has a center tap. Unipolar motors can step without having to reverse the direction of current in the coils, making the electronics simpler. However, because the center tap is used to energize only half of each coil at a time they typically have less torque than bipolar.

The design of the stepper motor provides a constant holding torque without the need for the motor to be powered and, provided that the motor is used within its limits, positioning errors don't occur, since stepper motors have physically predefined stations.

Steppers.jpg


Resources

RPM

stepper motors, controlled via a micro controller are easy to follow at what rpm they operate, and to be adjusted e with dc motors, it is a fixed rpm with a small torque, at which the motor operates, and in order to adjust this, gear systems, pulleys .....there is more

Making things move is a book, very useful, please download it and look especially into Forces, Friction, and Torque (Oh My!) starting page 73 and then The Guts: Bearings, Couplers, Gears, Screws, and Springs page 189 till the end But also check out the website for useful bits and pieces

3d printing

lasercutting

Buying electronics

Here are some online options for getting electronics

diy enthusiasts, a bit pricey but very fast delivery, two dutch websites

here find almost anything

  • and conrad [[1]]

Workshop documentation

...end