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  United States Patent
Three Dimensional Display Using a Varifocal Mirror

Patent Number: 4,607,255
Date of Patent: Aug. 19, 1986
Inventors: Henry Fuchs (Pittsboro, N.C.) and Stephen M. Pizer (Chapel Hill, N.C.)
Assignee: The University of North Carolina at Chapel Hill, Chapel Hill, N.C.
Appl. No.: 524,664
Filed: Aug. 19, 1983
Int. Cl.: G09G 1/00, 3/00
U.S. Cl.: 340/755
17 Claims

Diagram Abstract
A three dimensional display utilizes a varifocal vibrating mirror which reflects the screen on a CRT. The varifocal mirror is vibrated at a rate synchronous with creation of frames on the point plotting CRT. A video source is utilized of the type having red, green and blue outputs utilized for normally creating color display. However, the coding is such that what would normally be interpreted as red, green and blue outputs of the video source are instead interpreted as x position, y position and intensity information for a CRT accepting x, y, and i signals. A depth or z coordinate is implicitly encoded in the video source at the position within a single frame of the video source where the corresponding (x, y and i) values are stored. This position can be the relative position on a magnetic or optical disc, or position around a magnetic drum. In one embodiment of the invention a raster graphics system utilizing a frame buffer is utilized. The frame buffer is divided into buckets, and the particular bucket within the frame buffer where an (x, y, i) display point is stored corresponds to the z value or depth coordinate of that point. Techniques are disclosed for interactive modification of three dimensional displays utilizing the look-up tables and registers in a standard raster graphics display system for achieving image rotation, transformation, scaling, spatial windowing, intensity windowing, cursor control, cursor inking, and blinking.

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