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IMAX is a proprietary system of high-resolution cameras, film formats, film projectors, and theaters known for having very large screens with a tall aspect ratio (approximately either 1.43:1 or 1.90:1) and steep stadium seating.
Graeme Ferguson Graeme Ferguson may refer to: * Graeme Ferguson (biathlete) (born 1952), British biathlete * Graeme Ferguson (filmmaker) Ivan Graeme Ferguson (October 7, 1929May 8, 2021) was a Canadian filmmaker and inventor. He was noted for co-inventing IM ...
, Roman Kroitor, Robert Kerr, and William C. Shaw were the co-founders of what would be named the IMAX Corporation (founded in September 1967 as Multiscreen Corporation, Limited), and they developed the first IMAX cinema projection standards in the late 1960s and early 1970s in Canada. IMAX GT is the large format as originally conceived. It uses very large screens of and, unlike most conventional film projectors, the film runs horizontally so that the image width can be greater than the width of the film stock. It is called a 70/15 format. It is used exclusively in purpose-built theaters and dome theaters, and many installations limit themselves to a projection of high quality, short documentaries. The high costs involved in the construction and maintenance of the dedicated buildings and projectors suggested the introduction of several compromises in the following years. To reduce costs, the IMAX SR and MPX systems were introduced in 1998 and 2004, respectively. The smaller projectors were used to retrofit existing theaters, so as to make IMAX available to multiplex and existing theaters, though losing much of the quality of the GT experience. Later came the introduction of the IMAX Digital 2K and IMAX with Laser 4K in 2008 and 2015 respectively, still limited in respect to the 70 megapixels of equivalent resolution of the original 15/70 film. Both technologies are purely digital and suitable to retrofit existing theaters. Since 2018, the Laser system has been employed to retrofit full dome installations, with limited results due to the large area of a dome screen.


History

The IMAX film standard uses 70 mm film run through the projector horizontally. This technique produces an area that is about 8.3 times as large as the 35 mm format, and about 3.4 times as large as 70 mm film run through the projector vertically.How Regular Movies Become "IMAX" Films
by Mark Wilson (Gizmodo.com, published May 29, 2009)
The desire to increase the visual impact of film has a long history. In 1929,
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introduced
Fox Grandeur 70mm Grandeur film, also called Fox Grandeur or Grandeur 70, is a 70mm widescreen film format developed by William Fox through his Fox Film and Fox-Case corporations and used commercially on a small but successful scale in 1929–30. Filmography ...
, the first 70 mm film format, but it quickly fell from use. In the 1950s, the potential of 35 mm film to provide wider projected images was explored in the processes of CinemaScope (1953) and VistaVision (1954), following multi- projector systems such as Cinerama (1952). While impressive, Cinerama was difficult to install and maintain, requiring careful alignment and synchronization of the multiple projectors. During Expo 67 in Montreal, the National Film Board of Canada's '' In the Labyrinth'' and Ferguson's ''Man and the Polar Regions'' both used complex multi-projector, multi-screen systems. Each encountered technical difficulties that led them to found a company called "Multiscreen", with the goal of developing a simpler approach.


Multiscreen Corporation

The single-projector/single-camera system they eventually settled upon was designed and built by Shaw based upon a novel "Rolling Loop" film-transport technology purchased from Peter Ronald Wright Jones, a machine shop worker from Brisbane, Australia. Film projectors do not continuously flow the film in front of the bulb, but instead "stutter" the film travel so that each frame can be illuminated in a momentarily-paused still image. This requires a mechanical apparatus to buffer the jerky travel of the film strip. The older technology of running 70 mm film vertically through the projector used only five sprocket perforations on the sides of each frame; however, the IMAX method used fifteen perforations per frame. The previous mechanism was inadequate to handle this intermittent mechanical movement that was three times longer, and so Jones's invention was necessary for the novel IMAX projector method with its horizontal film feed. As it became clear that a single, large-screen image had more impact than multiple smaller ones and was a more viable product direction, Multiscreen changed its name to IMAX. Co-founder Graeme Ferguson explained how the name IMAX originated:
... the incorporation date
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September 1967. ... he name changecame a year or two later. We first called the company Multiscreen Corporation because that, in fact, was what people knew us as. ... After about a year, our attorney informed us that we could never copyright or trademark Multivision. It was too generic. It was a descriptive word. The words that you can copyright are words like Kleenex or Xerox or Coca-Cola. If the name is descriptive, you can't trademark it so you have to make up a word. So we were sitting at lunch one day in a Hungarian restaurant in Montreal and we worked out a name on a placemat on which we wrote all the possible names we could think of. We kept working with the idea of maximum image. We turned it around and came up with IMAX.
The name change actually happened more than two years later, because a key patent filed on January 16, 1970, was assigned under the original name Multiscreen Corporation, Limited. IMAX Chief Administration Officer Mary Ruby was quoted as saying, "Although many people may think "IMAX" is an
acronym An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in '' NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, a ...
, it is, in fact, a made-up word."


IMAX Corporation

'' Tiger Child'', the first IMAX film, was demonstrated at Expo '70 in Osaka, Japan. The first permanent IMAX installation was built at the Cinesphere theatre at Ontario Place in Toronto. It debuted in May 1971, showing the film '' North of Superior''. The installation remained in place during Ontario Place's hiatus for redevelopment. The Cinesphere was renovated while Ontario Place was closed and re-opened on November 3, 2017, with IMAX 70 mm and IMAX with laser illumination. During Expo '74 in Spokane, Washington, an IMAX screen that measured was featured in the US Pavilion (the largest structure in the expo). It became the first IMAX Theatre to not be partnered with any other brand of movie theatres. About five million visitors viewed the screen, which covered the viewer's total visual field when looking directly forward. This created a sensation of motion in most viewers, and motion sickness in some. Another IMAX 3D theatre was also built in Spokane; however, its screen size is less than half. Due to protests, the City of Spokane officials decided to work with the IMAX Corporation to demolish the theatre, under the condition they renovate the former US Pavilion itself into IMAX's first permanent ''outdoor'' giant-screen theatre. The plan was to use material on the inside of the structure similar to that used when first constructed. However, it was expected to last only five years, due to weather conditions destroying previous materials. Concept art has been released in videos featured on Spokane's renovation site, and its budget revealed that seating is planned for more than 2,000. The first permanent IMAX Dome installation, the Eugene Heikoff and Marilyn Jacobs Heikoff Dome Theatre at the Reuben H. Fleet Science Center, opened in
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...
's Balboa Park in 1973. It doubles as a
planetarium A planetarium ( planetariums or ''planetaria'') is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. A dominant feature of most planetarium ...
theater. The first permanent IMAX 3D theatre was built in
Vancouver Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the most populous city in the province, the 2021 Canadian census recorded 662,248 people in the city, up from 631,486 in 2016. Th ...
, British Columbia, for '' Transitions'' at Expo '86, and was in use until September 30, 2009. It was located at the tip of Canada Place, a Vancouver landmark.


Digital projection

In 2008, IMAX extended its brand into traditional theaters with the introduction of Digital IMAX, a lower-cost system that uses two 2K digital projectors to project on a 1.90:1 aspect ratio screen. This lower-cost option, which allowed for the conversion of existing
multiplex theater A multiplex is a movie theater complex with multiple screens within a single complex. They are usually housed in a specially designed building. Sometimes, an existing venue undergoes a renovation where the existing auditoriums are split into s ...
auditoriums, helped IMAX to grow from 299 screens worldwide at the end of 2007 to over 1,000 screens by the end of 2015. , there were 1,302 IMAX theatres located in 75 countries, of which 1,203 were in commercial multiplexes. The switch to digital projection came at a steep cost in image quality, with 2K projectors having roughly an order of magnitude less resolution than traditional IMAX film projectors. Maintaining the same 7-story screen size would only make this loss more noticeable, so many new theaters were instead built with significantly smaller screens. These newer theaters with much lower resolution and much smaller screens soon began to be referred to by the derogatory name "LieMAX", particularly because the company still marketed the new screens similarly to the old ones, without making the major differences clear to the public, going so far as to market the smallest "IMAX" screen, having 10 times less area, similarly to the largest while persisting with the same brand name. Since 2002, some feature films have been converted into IMAX format for displaying in IMAX theatres, and some have also been (partially) shot in IMAX. By late 2017, 1,302 IMAX theatre systems were installed in 1,203 commercial multiplexes, 13 commercial destinations, and 86 institutional settings in 75 countries, with less than a quarter of those having the capability to show 70mm film at the resolution of the large format as originally conceived.


Technical aspects


Camera


Film cameras

The IMAX cinema process increases the
image resolution Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies how cl ...
by using a larger film frame; in relative terms, a frame of IMAX format film has three times the theoretical horizontal resolution of a frame of 35 mm film. To achieve such increased image resolution, which IMAX estimates at approximately 12,000 lines (6,000 line pair modulations) of horizontal resolution (12K),
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stock passes horizontally through the IMAX movie camera, 15 perforations at a time. At 24 frames per second, this means that the film moves through the camera at per minute (just over 6 km/h). In a conventional 65 mm camera, the film passes vertically through the camera, five perforations at a time, or per minute. In comparison, in a conventional 35 mm camera, 35 mm film passes vertically through the camera, at four (smaller) perforations at a time, which translates to per minute. In the Todd-AO 70 mm-format of widescreen cinema, the image area of a 65 mm film-frame is ; in the IMAX-format of widescreen cinema, the film-frame dimensions are . To match the standard image resolution of the moving image produced with the film-speed of 24 frames per second, an IMAX film requires three times the length of (negative) film stock required for a 65 mm film of comparable scope and cinematic technique. In March 2022, IMAX announced a new initiative in cooperation with Kodak, Panavision, and FotoKem to develop "a new fleet of next generation IMAX film cameras", with a goal to deploy the first four units in the next two years. Christopher Nolan and
Jordan Peele Jordan Haworth Peele (born February 21, 1979) is an American actor, comedian, and filmmaker. He is best known for his film and television work in the comedy and horror genres. Peele's breakout role came in 2003, when he was hired as a cast membe ...
are among a group of advisors, made up of filmmakers and cinematographers, assisting in identifying new specs and features for the prototype development phase.


Phantom 65 IMAX 3D digital camera

In 2011, IMAX announced a 4K 3D digital camera. The camera was developed alongside Vision Research and AbelCine, integrating two Phantom 65 engines. A prototype camera was used for the documentary '' Born to be Wild'', in which approximately 10% of the finished film was shot with the system. The company has said they have no intention of replacing the higher resolution film cameras with the new digital camera, but the latter can be used in scenes that require a lightweight or relatively small 3D camera. While IMAX has completed the production camera and has placed it in service on several films, they have no plans to produce an IMAX film solely with the new digital system. '' Transformers: Age of Extinction'' is the first feature film partially filmed with the Phantom 65 IMAX 3D camera.


ARRI Alexa IMAX digital camera

In 2015, IMAX announced a 2D digital camera that was developed alongside Arri, the camera being based on the latter company's Arri Alexa 65 technology. The first production to use the camera was '' Captain America: Civil War''. The Russo brothers have stated that they solely used the Arri Alexa IMAX on '' Avengers: Infinity War'' (2018) and '' Avengers: Endgame'' (2019). For '' Transformers: The Last Knight'', two ARRI Alexa IMAX cameras were combined in a rig to provide native 3D, with the film containing 98% of IMAX footage.


Blackmagic URSA Mini Pro 12K

In 2020, Blackmagic Design announced a 12K camera that can be used for shooting large-format IMAX.


IMAX certified cameras

In September 2020, IMAX launched the "Filmed In IMAX" program, which certifies high-quality digital cameras that can be used to create IMAX-format films. As the scope of certified cameras expands, it will be easier for filmmakers to create films to meet the projection needs of the IMAX giant screen theater. None of the certified cameras in the table below yet does 12K. The Blackmagic URSA Mini Pro 12K is not in the table below because it is not yet certified. '' Top Gun: Maverick'' (shot with the Sony CineAlta Venice) and '' Dune'' (shot with the Arri Alexa LF and Mini LF) were among the first films that used IMAX-certified cameras. Other films between 2021 and 2023 that captured with this program are '' The Suicide Squad'' (shot with the Red Ranger Monstro and Komodo), '' Shang-Chi and the Legend of the Ten Rings'' (shot with the Arri Alexa LF and Mini LF), '' The Battle at Lake Changjin'' and '' The Battle at Lake Changjin II'' (shot with the Red Ranger Monstro), '' Eternals'' (shot with the Arri Alexa LF and Mini LF), '' Doctor Strange in the Multiverse of Madness'' (shot with Panavision Millennium DXL2), '' Thor: Love and Thunder'' (Shot with the Arri Alexa LF and Mini LF), '' Black Panther: Wakanda Forever'' (Shot with the Sony CineAlta Venice), '' The Marvels'' (Shot with the Arri Alexa LF and Mini LF) and '' Dune: Part Two'' (Shot with the Arri Alexa LF and Mini LF).


Film stock

The IMAX format is generically called "15/70" film, the name referring to the 15 sprocket holes or perforations per frame. The film's bulk and weight require horizontal platters, rather than conventional vertically mounted film reels. IMAX film is fed through the projector horizontally, and the film is drawn from the inner circumference of the platter, not from the outer circumference like in conventional film reels. A system is in place to keep the film in the outer circumference from flying outwards due to centrifugal force while the platter is spinning. IMAX film is shipped to theaters in several small reels that are spliced into one continuous length that is then wound into a platter, a process that may take hours to complete. Films may be several kilometers in length: ''Avatar'', which was 2:45 hours in duration, was close to long. Platters are handled using special forklifts. IMAX platters range from diameter to accommodate 1 to 2.75 hours of film. Platters with a 2.5 hour feature film weigh . IMAX uses ESTAR-based print film in their 15/70 rolling-loop film projection systems. ESTAR-based print film provides greater precision. The chemical development process does not change the size or shape of ESTAR print film, and IMAX's pin registration system (''especially that of the camera mechanism'') does not tolerate either sprocket-hole or film-thickness variations, but the film can still swell or shrink under varying temperature and humidity. This requires projection booths to be kept at a temperature of between 20 and 23.8 °C and a humidity of 50%. The film is too large to be moved using its sprockets, so they are instead used for registration, to aid in aligning the film. A feature film platter can cost to print. The camera negative is actually 65 mm film stock, but it runs horizontally and with 15 perforations per frame. The camera, like the projector, has a vacuum system; this makes the camera noisy, forbidding the recording of quiet scenes. The camera has enough film for three minutes of shooting. The large frame of the film also imposes optical limitations such as an extremely shallow depth of field when shooting with an open aperture.


Soundtrack – double-system

To use more of the image area, IMAX film does not include an embedded soundtrack. Instead, the IMAX system specifies a separate six-channel magnetic film, recorded and played back on a film follower locked to picture, just as Vitaphone had been (utilizing 16-inch 33 1/3 RPM electrical transcription discs) in the early 20th century, and was the same technology used to provide the 7-channel soundtrack accompanying films photographed and exhibited in the Cinerama process in the mid-1950s. By the early 1990s, a separate DTS-based 6-track digital sound system was used, similarly locked to the projector by a SMPTE time code synchronization apparatus, the audio played off a series of proprietarily encoded CD-ROM discs. In the late 1990s, IMAX upgraded this system to use a hard drive that carries a single uncompressed audio file that contains the six channels. These are converted directly to analogue rather than processed through a decoding method such as DTS. Like conventional theatres, IMAX theatres place speakers both directly behind the acoustically transparent screen, and around the theatre to create a "surround sound" effect. IMAX also provides a "top center" speaker in addition to the centre speaker found in conventional theatres. This extra channel allows the sound mix engineers to take advantage of the screen's greater height.


Projectors

Transporting the large film stock through the optical system presented challenges for both the camera and the projector. Conventional 70 mm systems were not steady enough for the 586× magnification. On the projector side, William Shaw adapted an Australian patent (no. 291,375) for film transport called the "rolling loop" by adding a compressed air "puffer" to accelerate the film, and put a cylindrical lens in the projector's "aperture block". The rolling loop mechanism is used to move the film in projectors and cameras; the sprockets in the film are only used for registration as the film is too large to be moved with sprockets at the necessary speeds for projection and filming without damage. The projector uses a vacuum to pull the film into contact with this lens. Thus the " field flattener" flattens the image field. The lens is twice the height of the film and connects to a
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so it can be moved up or down while the projector is running. This way, if a piece of dust comes off the film and sticks to the lens, the projectionist can switch to a clean portion of the lens at the push of a button. The lens also has "wiper bars" made of a felt or brush-like material that wipes dust off the lens as it moves up or down. The projector uses a vacuum to keep the film flat and oriented correctly for projection. The shutter of an IMAX projector is also kept open for longer than a 35 mm projector shutter to increase image brightness. IMAX projectors are pin-stabilized; this means that four registration pins engage the perforations at the corners of the projected frame to ensure perfect alignment. Shaw added cam-controlled arms to decelerate each frame to eliminate the microscopic shaking as the frame "settled" onto the registration pins. The projector's shutter is open around 20% longer than in conventional equipment, and the light source is brighter. The xenon short-arc lamps are made with a thin envelope of fused quartz and contain xenon gas at a pressure of about 25 atmospheres (). Because of this, projectionists are required to wear protective body armor when changing or handling the lamp in case it breaks (e.g., due to a drop to the floor) because of the danger from flying quartz shards propelled by the high pressure of the xenon gas within; this applies to all projection xenon lamps. An IMAX xenon lamp runs on DC power, lasts for 1,000 hours and requires its own pump and water cooler. The projector's optics also require compressed air cooling. An IMAX projector weighs up to 1.8 tonnes (2 short tons) and is over tall and long. The projector is raised and locked into position before each screening. IMAX Corporation has released four projector types that use its 15-perforation, 70 mm film format: GT (Grand Theatre), GT 3D (dual rotor), SR (Small Rotor), and MPX, which was designed for retrofitted theatres. In July 2008, the company introduced a digital projection system, which it has not given a distinct name or brand, designed for multiplex theatres with screens no wider than . All IMAX projectors, except the standard GT system, can project 3D images. GT 3D projectors require two separate lamps and polarized projection optics.


Digital projection

The digital cinema IMAX projection system, debuted in 2008, is designed for use with shorter 1.89:1 aspect ratio screens. The system uses two 2K projectors that can present either 2D or 3D content in
DCI DCI may be an abbreviation for: Technology * D-chiro-inositol, an isomer of inositol * Data, context and interaction, an architectural pattern in computer software development * Direct Count & Intersect, an algorithm for discovering frequent se ...
or IMAX Digital Format (IDF; which in itself is a superset of DCI). IDF initially used 2K-resolution Christie xenon projectors, with a Texas Instruments Digital Light Processing (DLP) engine, but in 2012 IMAX announced that they would be switching to Barco as their primary supplier. The two 2K images are projected superimposed on each other with a half-pixel offset, using
super-resolution imaging Super-resolution imaging (SR) is a class of techniques that enhance (increase) the resolution of an imaging system. In optical SR the diffraction limit of systems is transcended, while in geometrical SR the resolution of digital imaging sensors i ...
to increase the perceived resolution to approximately 2.9K. For 3D presentations, one projector is used to display the image for each eye, while 2D presentations use the superimposed images to allow for a brighter 22- foot lambert image. The Digital IMAX projection system includes a proprietary IMAX Image Enhancer that modifies the output of the digital media server based on feedback from cameras and microphones in the auditorium, and maintains alignment with sub-pixel accuracy. Mainly because the system facilitates inexpensive distribution of IMAX features, the company announced in February 2012 that they were re-renovating specially selected locations around the world to present both 70 mm analog as well as digital presentations. To do so, IMAX developed a rail system that moves the projectors in and out to accommodate either a full-frame film print or a digital-only release. These theaters were prepared in time for the release of '' The Dark Knight Rises'' in July 2012.


Laser projection

In April 2012, IMAX began testing a new 4K laser projection system, based on patents licensed from Eastman Kodak. Like the 3D film and digital systems, it used two projectors, but it improved over the smaller digital screens by retaining the traditional IMAX aspect ratio and let films be shown on screens wide or more. In December 2014, IMAX began rolling out its new Dual 4K laser projector system, dubbed "IMAX with Laser", with the first installation occurring at the Cineplex ScotiaBank Theatre in
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. The system allows digital projection on the full 1.43:1 aspect ratio surface of a traditional IMAX screen, but can also be used on wider screens such as the 1.89:1-aspect-ratio
TCL Chinese Theater Grauman's Chinese Theatre (branded as TCL Chinese Theatre for naming rights reasons) is a movie palace on the historic Hollywood Walk of Fame at 6925 Hollywood Boulevard in Hollywood, Los Angeles, Hollywood, Los Angeles, California, United States. ...
. The system replaces the xenon arc lamp of a traditional digital projector with a laser light source, and is capable of 60 fps with "50 percent greater" brightness than the Digital Cinema Initiatives spec, a contrast ratio "double" that of IMAX 15/70 mm film projection and "higher" than the 2,500:1 contrast ratio of IMAX's xenon lamp-based projection systems, and displaying the full
Rec. 2020 ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of ultra-high-definition television (UHDTV) with standard dynamic range (SDR) and wide color gamut (WCG), including picture ...
color gamut/space. The system also features a new 12-channel surround sound system, which adds an additional speaker on either side of the theater as well as four new overhead speakers. While still not matching the theoretical resolution of traditional IMAX film, which is estimated at up to 12,000 lines of horizontal resolution on the 65 mm camera negative (12K) and approximately 6,000 on a 35 mm release print (6K), the new laser system features dual- 4K resolution projectors, each capable of displaying four times the detail of one Digital IMAX projector. Like Digital IMAX, images from the two projectors are projected superimposed on each other with a half-pixel offset, using
super-resolution imaging Super-resolution imaging (SR) is a class of techniques that enhance (increase) the resolution of an imaging system. In optical SR the diffraction limit of systems is transcended, while in geometrical SR the resolution of digital imaging sensors i ...
, which makes the perceived resolution greater than 4K. In-theater cameras and microphones are used to automatically calibrate the projectors and sound system between showings. For 3D presentations, one projector is used to display the image for each eye, while 2D presentations use the superimposed images to allow for a brighter image. For 3D presentations, IMAX with Laser systems use dichroic filter glasses, similar to those used by Dolby 3D, as opposed to the linear polarization glasses used in Digital IMAX theaters. On April 24, 2018, IMAX announced that they would begin rolling out a new single-unit version of their laser projector system later that year, with this iteration designed to replace the IMAX Xenon digital projection system for 1.89:1 screens.


Theatres

IMAX theatres are described as either "Classic Design" (purpose-built structures), or "Multiplex Design" (retrofitted auditoriums). Classic IMAX theatre construction differs significantly from conventional theatres. The increased resolution lets the audience be much closer to the screen. Typically all rows are within one screen height – conventional theatre seating runs 8 to 12-screen heights. Also, the rows of seats are set at a steep angle (up to 30° in some domed theatres) so that the audience is facing the screen directly. The world's largest IMAX screen currently stands in
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near
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,
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and measures . Until 2021, the largest operating IMAX screen was located within the Melbourne Museum in
Melbourne Melbourne ( ; Boonwurrung/ Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a me ...
, Australia, measuring . Until 2016, the world's largest IMAX screen had been in Darling Harbour,
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, Australia, measuring , until it was closed for reconstruction. Once completed, the new Sydney IMAX will include an even larger screen ensuring it retains the record as the world's largest 1.43:1 IMAX screen.


Variations


Dome and Omnimax

In the late-1960s, the San Diego Hall of Science (now known as the Reuben H. Fleet Science Center) began searching North America for a large-format film system to project on the dome of their planned tilted dome
planetarium A planetarium ( planetariums or ''planetaria'') is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. A dominant feature of most planetarium ...
. The standard IMAX projector was unsuitable for use inside a dome because it had a tall lamp house on top. IMAX Corporation redesigned its system, adding an
elevator An elevator or lift is a cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or decks of a building, vessel, or other structure. They ar ...
to lift the projector to the center of the dome from the projection booth below. Spectra Physics designed a suitable lamphouse that took smaller, lamps and placed the bulb behind the lens instead of above the projector. In 1970, Ernst Leitz Canada, Ltd. (now ELCAN Optical Technologies) won a contract to develop and manufacture a fisheye lens projection system optimized to project an image onto a dome instead of a flat screen. The dome system, which the San Diego Hall of Science called "Omnimax", uses films shot with a camera equipped with a fisheye lens that squeezes a highly distorted anamorphic 180° field of view onto the 65 mm IMAX film. The lens is aligned below the center of the frame, and most of the bottom half of the circular field falls beyond the edge of the film. The part of the field that would fall below the edge of the dome is masked. When filming, the camera is aimed upward at an angle that matches the tilt of the dome. When projected through a matching fisheye lens onto a dome, the original panoramic view is recreated. Omnimax wraps 180° horizontally, 100° above the horizon and 22° below the horizon for a viewer at the center of the dome. Omnimax premiered in 1973, showing '' Voyage to the Outer Planets'' (produced by Graphic Films) and '' Garden Isle'' (by Roger Tilton Films) on a double bill. IMAX has since renamed the system "IMAX Dome", but some theaters (primarily those opened before the 2000s) continue to call it "Omnimax". IMAX Dome theatres are used in theme parks and many North American museums, particularly those with a scientific focus, where the technical aspects of the system may be highlighted as part of the attraction. The projection room is often windowed to allow public viewing of the equipment in operation, and it is often accompanied by informational placards like other exhibits. For some theaters, before the show begins, the screen can be backlit to show the speakers and girders behind it. The screen may be a permanent fixture, such as at the Museum of Science and Industry ( Henry Crown Space Center) in Chicago, Illinois; the Fort Worth Museum of Science and History; the Franklin Institute in Philadelphia, Pennsylvania; the St. Louis Science Center; Boston's Museum of Science; Richmond's Science Museum of Virginia; the Charlotte Observer IMAX Dome Theatre at Discovery Place, Charlotte, North Carolina; Birmingham, Alabama's McWane Science Center; US Space and Rocket Center in Huntsville, Alabama; the Cincinnati Museum Center at Union Terminal and Great Lakes Science Center in Cleveland, Ohio, and the Ontario Science Centre in Toronto, Ontario, Canada. Alternatively, the dome may be lowered and raised as needed, such as at the Science Museum of Minnesota, and the former installation at the Canadian Museum of History (where it shared an auditorium with a standard IMAX screen, all replaced with a Barco CINE+ digital theatre system in 2016). The entire dome could be raised to show flat-screen features, and repositioned for immersive features. While the majority of museum installations focus on educational and documentary films, on special occasions entertainment films are also shown, such as '' Charlie and the Chocolate Factory'' at the Oregon Museum of Science and Industry. The largest screen in North America is at the Science World in Vancouver, British Columbia, which has a dome screen in size. Due to the age of the IMAX Dome format as well as its entirely analogue nature, some theatres may opt to replace their existing IMAX Dome systems with newer, more versatile digital systems. Examples of former IMAX Dome theatres that have had their IMAX equipment replaced with newer equipment include Tietomaa Science Centre in
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(which replaced its IMAX 8/70 equipment from 1988 with a Barco DP4K-32B 4K projection system in 2013), the Omni-Theatre at Science Centre Singapore, the National Museum of Natural Science in Taichung,
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northe ...
(which both had their original IMAX Dome 1570 projection systems installed respectively in 1987 and 1985 replaced with Evans & Sutherland
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8K digital systems in 2015), and the Jennifer Chalsty Planetarium at Liberty Science Center in
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, which replaced its IMAX Dome 1570 projection system from 1993 (when built was the largest IMAX Dome/OMNIMAX theatre in the world) with an Evans & Sutherland Digistar 6 "True8K" digital system in 2017. In November 2018, the Hackworth IMAX dome in The Tech Museum (now The Tech Interactive) replaced its 70 mm IMAX projector with a 4K IMAX Laser projector. It became the first digital IMAX Laser dome theater in the world.


3D

To create the illusion of depth, the IMAX 3D process uses two separate camera lenses that represent the left and right eyes. The lenses are separated by a distance of , the average distance between a human's eyes. Two separate rolls of film are used to capture the images they produce. The IMAX 3D camera weighs over . By projecting the two films superimposed on the screen and using one of several available methods to direct only the correct image to each eye, viewers see a 3D image on a 2D screen. One method is to use polarizing filters to oppositely polarize the light used in projecting each image. The viewer wears glasses with polarizing filters oriented to match the projector filters, so that the filter over each eye blocks the light used to project the images intended for the other eye. In another method, the two projections rapidly alternate. While one image is being shown, the projection of its mate is blocked. Each frame is shown more than once to increase the rate and suppress flicker. The viewer wears shutter glasses with
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shutters that block or transmit light in sync with the projectors, so each eye sees only the images meant for it. Several of the early films that had been produced in digital 3D for release in conventional theaters were also presented in IMAX 3D, including '' Avatar'', '' Gravity'' and '' The Amazing Spider-Man''. The first full-color IMAX 3D film was the 1986 short documentary '' Transitions'', produced for Expo 86 in Vancouver.


HD

Variations on IMAX included the 48 frames per second IMAX HD process, which sought to produce smoother, more lifelike motion, while also reducing the blurring of moving objects, by doubling the normal film rate. The IMAX HD system was tested in 1992 at the Canada Pavilion of the Seville Expo '92 with the film ''
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''. Higher production costs, and the high "wear-and-tear" on the prints and projectors, doomed the IMAX HD system, but, not before many theatres had been retrofitted to project at 48 frames, especially in Canada, in order to play ''Momentum''. In the 1990s theme parks in Thailand, Germany, and Las Vegas used IMAX HD for their Motion Simulator rides. The Disney parks attraction
Soarin' Over California ''Soarin, also known as ''Soarin' Around the World'', ''Soaring Over the Horizon'' and ''Soaring: Fantastic Flight'', is a flight simulator, motion simulator attraction at Disney California Adventure, Epcot, Shanghai Disneyland, and Tokyo Disn ...
features a modification of both IMAX HD and IMAX Dome, projecting in 48 frames per second.


Digital

Because 70 mm film and projectors are costly, d