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Projection mapping, also known as video mapping and spatial augmented reality, is a projection technology used to turn objects, often irregularly shaped, into a display surface for video projection. These objects may be complex industrial landscapes, such as buildings, small indoor objects or theatrical stages. By 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 interact with a projector to fit any desired image onto the surface of that object. This technique is used by artists and advertisers alike 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 audio-visual narrative.
Although the term projection mapping is relatively new, the technique dates back to the late 1960s, where it was referred to as video mapping, spatial augmented reality, or shader lamps. One of the first public displays of projections onto 3D objects was debuted in 1969, when Disneyland opened their Haunted Mansion ride. The ride used fake disembodied heads as objects which had 16mm film projected onto them to make them appear animated. 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. The first time the concept of projection mapping was investigated academically  was at the University of North Carolina at Chapel Hill in the late 1990s, where scholars worked on a project called Office of the Future to connect offices from different locations by projecting people into the office space as if they were really there. 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. Then, place each video on to its designated surface. Alternatively one may choose to map the entire scene in 3D and attempt to project and mask the image back onto its framework. The next step is defined as "masking," which means 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 need to be defined for where the object is placed in relation to the projector, the XYZ orientation, position, and lens specification of the projector have to result to a determined virtual scene. One such tool to help achieve this end is BLAM! add-on for blender 3D's open source 3D animation suite. Adjustments are commonly needed and made by manually tweaking either the physical or virtual scene for best results. Large projectors with 20,000 lumens or larger are used for large-scale projections such as on city skyscrapers. Otherwise, for smaller productions, a projector with a basic lower lumens will work. A 2200 lumen projector is adequate for projections under indoor light or theatrical lighting in most cases. Video mapping software such as MadMapper, Qlab, Troixatronix's Isadora, FaçadeSignage and VPT 6.0 are all downloadable for use in projects like these, though Adobe Photoshop, Adobe After Effects, Blender Blam!, and other packages can also be used by a creative artist. Also, extensible open-source software frameworks such as MPM (Multi-Projector-Mapper) are available among others. Projection mapping can be separated into four categories:
- VJ'ing or VeeJay-ing (video Jockeying) used where live events are augmented by (often interactive to music) projections which are fully dynamic, controlled live, and consist of pre-programmed videos and combinations of effects and effect overlays.
- Theatrical: where projections are preset and scenes are "cued" on demand, usually in a set order, in conjunction with dance or onstage performance, often interactive.
- Static/Interactive: where a display is set up and loops or interacts with the environment and viewers via programming.
- Video: where a generally long segmented show is present as a single fluid video that is not interactive and plays from beginning to end.
Productions, advertisement and art
Projection mapping first came to prominence through guerrilla advertising campaigns and video jockeys for electronic musicians. Large companies such as Nokia, Samsung, Unilever Pakistan, Pakistan Tobacco company, Bank Alfalah, Brighto Paints, Benson & Hedges, John Players Gold Leaf and BMW have since used video projections to create campaigns for their products in major cities across the world. These advertising campaigns commonly use mapping techniques to project scenes onto the sides of buildings. Projection mapping can also be interactive, as Nokia Ovi Maps did a project in which the projections would mimic people's movements.  Projection mapping has been used at conferences as a means of decoration or immersing audience members in an experienced-based theme. This can be as elaborate as projecting onto a flat surface, or projecting onto an unusual object such as a car or a chair. The festival Fête des Lumières in Lyon, a festival to honour the Virgin Mary, has recently also started incorporating 3D mapping into their productions, creating the illusion of a giant pinball machine on the side of a building. Common techniques for these performances included both 3-D mapping techniques and 3D projection to create the illusion of depth, as well as motion such as crumbling buildings.
In the electronic dance music (EDM) community, it is becoming increasingly common for DJs to accompany their music with synced visuals. Though normal projection screens are commonly used, some visual artists are beginning to create custom made, 3D installations to project onto. Many EDM artists employ projection mapping techniques at many of their shows. Artists who are solely visual also use projection mapping as a means of creative expression, believing that it can enhance existing creative mediums such as painting and drawing.
Artists may use it as an avant garde form of expression as it is new technology that can turn their creative ideas into 3D projections, connecting with audiences in a new way. Video projections have appeared in urban centres such as New York City and London, where artists have used guerilla projections in public without any necessary approval. This way, artists can show their work in any location as anything and anywhere can be a canvas. Often people also use it as a means of activism; the group Occupy Wall Street has used it to project onto the Verizon Wireless building in New York City as a means to visually spread the word that Occupy Wall Street is still alive.
Recently, projection mapping has been used more and more frequently by Walt Disney Imagineering and Walt Disney Creative Entertainment in the Disney Parks. Examples of this include, but are not limited to, The Magic, the Memories and You, Disney Dreams!, Celebrate the Magic, Once Upon a Time, Disneyland Forever, and, most recently, Happily Ever After (Magic Kingdom). 
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