Projection mapping
Projection mapping, similar to video mapping and spatial augmented reality, is a projection technique[1][2] used to turn objects, often irregularly shaped, into display surfaces for video projection. The objects may be complex industrial landscapes, such as buildings, small indoor objects, or theatrical stages. Using specialized software, a two- or three-dimensional object is spatially mapped on the virtual program which mimics the real environment it is to be projected on. The software can then interact with a projector to fit any desired image onto the surface of that object.[3] The technique is used by artists and advertisers who can add extra dimensions, optical illusions, and notions of movement onto previously static objects. The video is commonly combined with or triggered by audio to create an audiovisual narrative. In recent years the technique has also been widely used in the context of cultural heritage, as it has proved to be an excellent edutainment[4] tool.
History[edit]
Although the term "projection mapping" is relatively new, the technique dates back to the mid-20th century. Josef Svoboda, a Czech scenographer, debuted Lanterna Magika at Expo 58, the 1958 Brussels World Fair.[5] Lanterna Magika was a live performance that featured singers, dancers, and musicians performing against a backdrop of projected film footage. Günther Schneider-Siemssen was a German set designer, who coined the phrase, "painting with light.[6] He used Pani projectors to create large-scale projections for operas. In the late 1960s, audiences referred to projection mapping as, "the Madame Leota effect,[7]" based on the use of the technique in Disney's Haunted Mansion. Disneyland debuted a projection effect in 1969, when they opened their Haunted Mansion attraction, which featured singing three-dimensional busts. The singers' faces were filmed on 16mm film and projected onto busts of their faces to make the busts appear animated.[8] Another early example of projection mapping was in the 1967 TV movie Magical Mystery Tour during the Blue Jay Way scene, where images were projected onto George Harrison, including a cat's face and a headless male torso with the words "Magical Mystical Boy" written on its chest.[9]
The next record of projection mapping is from 1980, when installation artist Michael Naimark filmed people interacting with objects in a living room and then projected it in the room, creating illusions as if the people interacting with the objects were really there.[10][11]
In 1984 the Stephen Sondheim original Broadway production of Sunday in the Park With George, written and directed by James Lapine, was the first known use of projection mapping in a Broadway musical or play.[12] It was used at the end of Act II, in the Chromolume #7 special effects sequence designed by Bran Ferren[13] to project geometrically-correct moving cinematic images onto the surface of the 4' diameter sphere topping the Chromolume device. Due to the brightness limitations of video projection at the time, the images were projected using 7000w xenon-illuminated 35mm motion picture film (at 48 frames per second). The film's images were digitally pre-distorted to map correctly onto the sphere from the high projection angle in the Booth theater.
The first time the concept of projection mapping was investigated academically[14] was at the University of North Carolina at Chapel Hill in the late 1990s, where a team led by Ramesh Raskar worked on a project called Office of the Future, to connect offices in different locations by projecting people into an office space as if they were really there.[15] By 2001, more artists began using projection mapping in artwork, and groups such as Microsoft began experimenting with it as a means of technological advancement.
After the object which will be projected on is chosen or created, software is used to map the corners of the video to the surfaces. First, one must choose the images or video to project. Each video is then placed on its designated surface. Alternatively, one may map the entire scene in 3D and attempt to project and mask the image back onto its framework. The next step is masking, using opacity templates to actually "mask" the exact shapes and positions of the different elements of the building or space of projection.
In 3D mapping, coordinates are defined for where the object is placed in relation to the projector. The projector's XYZ orientation, position, and lens specification result in a determined virtual scene.[16]
Adjustments are commonly made by manually adjusting either the physical or virtual scene for best results. Large projectors with 20,000 lumens output or greater are used for large-scale projections such as on city skyscrapers. Due to the scale and brightness some projects require, often large arrays of powerful projectors are combined into a single image through a method known as "edge blending" or "stacking".[17] The result is a much brighter projection that maintains its seamless look. This technique is used for most large projection-mapping shows, and requires skill and patience to be set up with specialised software. For smaller productions, smaller, lower-output projectors are sufficient. In most cases, a 2200-lumen projector is adequate for projections under indoor light or theatrical lighting.
Video mapping software can be used in projects like these, though Adobe Photoshop, Adobe After Effects and other packages can also be used by creative artists. Extensible open-source software frameworks are also available.
Projection mapping can be separated into four categories:
Activism[edit]
Projection mapping has also been used as a way to highlight political and social causes by groups such as Greenpeace and Led By Donkeys.[32][33] The White Cliffs of Dover are frequently used to project messages of protest,[34][35] support[36] and memorials.[37]