3D: The Basics

Henry Corrado

3D: History and Principles

Although the peak has been reached, it seems that almost no theme park attraction project, whether it be a simple theater or the most elaborate dark ride, escapes 3D technology.

For some of us, the 3D infatuation we are currently experiencing is our first exposure to 3D. However, research on stereo vision did not wait for the recent public enthusiasm for 3D movies, as we shall see, but started almost at the beginning of photography. As always with sound and image technology, theme parks have played a key role in the development and adoption of these processes.

Principle of 3D

Most of us have two eyes, which normally receive the same information in terms of color and amount of light. But these images are slightly different: while our eyes are both focused in the same direction, each has a slightly wider field inward. The right eye "overlaps" a bit on the left eye and vice versa, which allows you to see part of the volume of what is in our field of vision. The closer an object is, the better we can assess its volume. Inversely, we can not distinguish the volume of objects that are far from us, and appear in "2D", when they are over about two meters away. Our brain helps us get an idea of the volume of distant objects with the knowledge we have of their volume. If we replace houses and trees in the distance by abstract forms, we are lost, unable to appreciate their width and depth.

Our eyes are also equipped with autofocus. They can focus together on one nearby object, but then we lose the sharpness and depth of the notion of what is in the background. In contrast, if one focuses on a distant object, close objects appear double. Our brain instantly adjusts its parameters so that we are almost never aware of these phenomena, and can focus continually on what interests us. This intervention of the brain can not be emulated by any 3D process.

Knowing how we appreciate volumes helps us to understand that in order to create the illusion of volume, we need to show each eye different information. In practice, the opposite approach is most often adopted, ie, send information for both eyes and hide from the opposite eye.

Each image of a 3D movie is the 2D representation of what each eye sees. Our eyes are usually spaced about 7 cm. In practice, if the film director increases the spacing between the eyes (by spacing the cameras), it is possible to appreciate the depth of objects in the distance. Inversely, if lenses are very close to each other, it is possible to focus very sharply and have a good idea of the volume of nearby objects. The consultant's work on a 3D film is to determine those adjustments for each film shot.

The beginnings

Stereoscopic cameras were accessible in the U.S.A from the mid-18th century, allowing the public to easily create 3D still images. The first moving pictures were presented on individual viewers. Many experiments seem to have occurred in the late 19th century, but few documents or films remain that attest to these inventions.

The fascination for 3D goes back to the very origins of cinema as we know it. The first film projected on a screen, "The arrival of the train at La Ciotat" was re-shot a few years after its release in 1903 with two 35mm cameras, and shown on a single 35mm film using anaglyph .

"The arrival of the train at La Ciotat" is symptomatic of a few seconds film with absolutely no narrative interest. It contains a simple scene showing the arrival of the train in the station. Viewers of this short film came to discover the technical innovation: a projection larger than life on the big screen.

Thus, before becoming an art in itself, cinema was an attraction for fairs. Louis Lumière once said: "The cinema was born in fairs and exhibitions, and it will die there". History proved him right. The last movie projectors to be replaced are the large format ones found in special venues.

The first phase

It was not until 1915 that the Famous Players Film Company (soon to become Paramount Pictures) produced a series of short films in anaglyphic 3D: "Jim the Penman", "Niagara Falls" and "Rural America". These short films were more technical demonstrations than artistic prowess. While developments continued in America, in 1921 French director César Parolini released "Opium Dream", a short film of which we do not know much about the 3D technology used. The development of a viable 3D camera in the U.S. made possible the release of feature films in the years that followed, including "Power of Love" and the French film "Faust".

"Plastigrams" is an interesting concept: a series of educational shorts. The first was shown for two years in New York, before being re-released a few years later, with a soundtrack and physical effects. It was the first 4D film in history.

Production continued steadily in the following years in the United States and Europe, particularly "Napoleon" from Abel Gance (an extract is used in the attraction "CinéMagique" at the  Walt Disney Studios in Paris) shot with a double camera developed by André Debrie. However, Gance finally decided not to use the 3D sequences of the film, which was shown in its 3D version only in private screenings.

In 1929, a scene from "Midnight Frolic Zigfield" was proposed in 3D

The late 20s marked the end of this first wave. The studios were more interested in talking movies and wide screen presentations (the introduction of the 70 mm format as projection goes back to that time).

In 1935, Edwin H. Land presented a 3D technique to studios, not with color filters, but using instead polarized filters that allowed full color 3D images. At the time, the studios didn't show interest in his technique, which is the most widely used today.

During the war the German government used a process developed by Zeiss-Ikon to produce a series of propaganda films. The Russians joined the fray in 1940 with "Vikhodnoy deni v Moskva". For the World Expo 1940 in New York, two pavilions showed 3D movies: Chrysler and the oil industry consortium.

Apart from these documentaries and some passages in obscure B movies and Soviet films, 3D was almost absent from screens in the years that followed.

The second wave

The film industry is anything but charitable, it took the growing threat of television in the 50s to trigger the comeback of 3D movies.

The success of "Lions of Gulu" in 1952 encouraged studios to use 3D for a number of films, like "Bwana Devil", "Down the Hatch", "the Black Swan", "Now is the Time" and "Fort Ti"."House of Wax" in 1953 broke box office records. Most of those movies were also experiments for stereophonic sound reproduction techniques.

The films of this second 3D wave required complex projection equipment and a crew of skilled technicians in each theatre.

It is largely the complexity of the theaters’ technical setup that precipitated the end of this wave. Exhibitors had to invest in expensive equipment with no guarantee on the durability of the technology. The poor artistic quality of most 3D productions of this era did not help matters. This wave of 3D production ended around 1955, while Cinemascope and other widescreen formats came on stage.

Yet at the same time, events took place in Hungary that would have lasting consequences, and not just for 3D cinema. The director Félix Bodrossy decided to work on a 3D cinema process. By necessity, he excluded the use of two projectors, used in most 3D systems of the time. The only processes using a single film stock in those days had the two images side by side. The result was a roughly square projection format, or worse, a higher than wider picture. Bodrossy thought that was unacceptable.

He had the idea to divert a prism system used by the manufacturer Bolex to overlay two images in the space normally required for a single image on 35mm film. The result was an image wider than high, with a width / height ratio of 1.85:1.

This ratio was later adopted by Hollywood as the only non-anamorphic format for 35 mm (the Europeans continued to produce movies in 1.66:1 format before they surrendered). One can imagine that the 16:9 ratio used in video nowadays is based on the 1.85:1 movie ratio.

The other decisive contribution Bodrossy made was for sound reproduction. Stereo systems of the time were very complex, and relied mostly on separate, hard to sync film reproducers.

The monophonic sound of the great majority of films at the time was printed on the film stock itself in the form of an optical track containing variations proportional to sound intensity. This track was read by a photocell mounted on the projector. Bodrossy had the idea to add a second optical track on the other side of the image, creating the first optical stereo playback system for film.

This is nothing less than the technique that the Dolby Laboratories would use years later for the development of Dolby Stereo, which had a decisive impact on the film industry. However, Dolby placed two optical tracks next to one another to ensure compatibility between mono and stereo stock in theaters and film printing laboratories.

The 60s and 70s

Although not completely absent, 3D production was particularly discreet in the two decades that followed the boom of the 50s.  3D came back in force in the 70s with director Alan Shiliphan and his daughter Victoria. The latter distinguished herself by making a series of erotic films in 3D, using a process with two images side by side on a single film. "The Stewardesses" was a huge success in regard of 100 000 dollars it cost to produce. This film has recently been re-mastered for its re-release in current 3D theaters.
The process used by "The Stewardesses" was adapted and used for around thirty films in the 70s and 80s, the best known remaining "The Jaws 3D" and "Amityville 3D". Several other adult movies have taken advantage of 3D, like "Venus" in 1983, with the talented French artist Sophie Favier.

The 80s, parks and 3D

The "Stereovision" process used by Victoria and Shiliphan was relatively simple. However, it required replacing the theater's screen fabric by a metallic one. It also reduced quite significantly the resolution of the projected image and called for the use of an expensive and sensitive projection lens.

Parks have no compatibility issues and they are used to complex technical rigs. So naturally, it is in theme parks that the most spectacular experiments of 3D technology took place in the 70s and 80s.

Disney has been leading the pack, up to their innovation tradition. A 3D film was presented in 1983 in California, Florida and Japan. "Magic Journey" was a poetic fresco with no real narrative content. The next project for Disney, "Captain EO" in 1986 really laid the foundation for what would become modern "4D": physical and visual effects synchronized to the film.

Previous attempts were rather clumsy; effects triggered manually or the use of 50s B-movies employees, and the Six Flags attempt with "sensorium" that mixed scents and 3D cinema. The creators of this attraction quickly realized that the greater difficulty was not to generate scents, but to get rid of them!

Disney's "Captain EO" was followed by "Muppet Vision 3D" in 1991, "Honey I Shrunk the Audience" in 1994, "It's Tough to Be a Bug" at Animal Kingdom in 1998 and "Philarmagic" in 2003. In these projects, the use of special effects is incorporated early on in design work. The integration of these well designed effects helps the narration, which is unfortunately not the case nowadays in many 4D theaters. There are exceptions however, like "Terminator 2 3D" Universal, or "Spiderman" at Islands of Adventures which mix brilliant 3D projections, special effects and a thunderous ride. All these attractions are still in operation, demonstrating the talent and vision of their creators. Recently, visitors to Disney parks in the United States have been able to enjoy the spectacular 3D picture quality of the new "Star Tours II".

These high quality attractions have paved the way for productions of very unequal quality, in most cases hollow scenarios embellished by a few strobe and smoke effects.

Most of the major theme 3D park attractions use two 70mm films. For even larger screens, in the 80s Imax adapted their process for 3D. First, for documentaries such as "We are born stars" in 1985 and later for fictions, like "Wings of Courage" in 1996 (for the 2012 season, Tejix is renovating the Futuroscope theater in which this film is shown).

The involvement of the Imax corporation in 3D is such that the majority of Imax theaters around the world use Imax 3D.

James Cameron was so impressed by Imax 3D that he used if for "Ghosts of the Abyss in 2003". Undoubtedly, this move led him to shoot "Avatar" in 3D, which many consider the trigger for the current 3D infatuation


The 2000s

This decade marks the transition from film projectors to their digital counterparts. Nowadays, Video projectors can achieve resolutions, light levels, contrast and color fidelity that outperform film projectors.

As soon as a viable economic model was developed, film reels were replaced by hard drives. With digital video, showing a sharp 3D film is relatively simple. The technical barrier associated with the operation of 3D cinema has fallen, the film industry has been able to retain audiences in theaters partially thanks to 3D. While "Avatar" is considered the film that really launched digital 3D in cinemas, "Polar Express" and "Chicken Little" were the pioneers in the mid-2000s.


Because of digital technology, conventional cinemas can offer their patrons a perfectly sharp image quality, cutting the grass under the feet of parks that can no longer rely solely on the technical novelty of 3D. The trivialization of 3D, including at home, confines the use of 3D situations to where it contributes actively to narration, which not often the case in 4D attractions. It's a safe bet that good attraction designers will come up with creative ideas to use existing 4D theaters with spectacular attractions, giving the guests the experiences that are unique to theme parks.