A Volumetric Display or Volumetric Projector produces a voxel (3D pixel) image in the air similar to a hologram. The image produced by a volumetric projector is more likely to look like R2-D2's projection of Princess Leia in STAR WARS (episode IV) than a Holographic projector would. Like a Hologram, a Volumetric Projector 3D image can be seen from many angles and without wearing any 3-d glasses.
It is possible to use a pair of parabolic mirrors as a Volumetric 3D image projector, but it is simpler and more compact to use an ordinary eyeglass lens and an LED screen to achieve the same effect. 3D motion and animation has been demonstrated in the images projected by an eyeglass lens.
Another movie with an example of a 3D digital image volumetric projector is Paycheck, released in 2003, only shortly after the "eyeglass lens" method was invented. The invention was ignored due to its utter simplicity and use of Public Domain BASIC programming language, and then published on various websites as an open hardware invention. All of its parts were dated 1980, so it could have worked even then. The eyeglass 3D digital image projector is named "CUBE", "Build A Holodeck", and "Junk Volumetric Projector" on the internet.
Actuality Systems invented a Volumetric Display that looks like something inside a crystal ball and thus cannot project Princess Leia. It seemed a coincidence that both Actuality and Cube projected demo images of airplanes, until it was known that "the flying cube" demo on the eyeglass lens is a 3D animation of a plane flying over mountains, but the crystal ball's plane does not fly. Additionally, the crystal ball seems to require Windows, while the Cube will even continue "flying" if its old modem is disconnected from the BASIC computer.
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