Marks imagines the potential for user-generated content when users can use the controllers to take a standard 3-D object like a sword, and grab, stretch and deform it on-screen to create new custom objects with new properties.

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Holography is a means of producing a 3-D image of an object.

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These applications create images by constructing 3-D polygons that describe an entire object (see chart, above).

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Suddenly, Todashev knocked over a table -- knocking the FBI agent back into a wall -- and came at him with some sort of "long-handled object" that he'd grabbed from behind him, according to the official.

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The fourth "d" here is time, referring to an object that, once printed, is capable of changing shape (over time, naturally).

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Somebody in the audience asked Pettis if 3-D printers will someday be able to print any object you could possibly need.

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It uses a vehicle-mounted camera, object-recognition software and satellite positioning to create detailed 3-D maps of roads, pinpointing features such as pot-holes.

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To me (d) is the biggest lost opportunity for Microsoft of all and perhaps is the object lesson in what nearly three decades of monopoly buys you.

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When the reflected object beam and the reference beam are recombined, they create an interference pattern that encodes the 3-D image.

ENGADGET: Infrared holography lets rescuers see people through walls, fire, walls of fire (video)