Patent CA-2121054-C (CA)
Title: Apparatus for stereoscopically viewing imagery of scenes and objects
Inventor: PETHICK GERALD
IPC: G02B30/22
Filed: 1994-04-12
Granted: 2003-06-17
Abstract: Various types of apparatus which embody this invention provide means for stereoscopically viewing imagery of scenes or objects, without requiring that the viewers wear special glasses or other encumbrances. A stereoscopic effect is achieved by forming two independent images of a scene or object, one for the left eye and one for the right eye of one or more viewers. The various embodiments have several major elements in common. The first element is an array of lenses, all having the same focal length. These lenses are positioned on a surface to form an array, which is preferably regular and closely-packed and in which the centres of lenses are equidistant from each other. The lens centres lay on a surface which is planar for some, curved for others, and multifaceted for still other embodiments. For preferred embodiments of this invention, the lateral shapes of the lenses range from being circular to being those of equilateral triangles, squares, or regular hexagons.        A second major element is an array of stereoscopically-related, displaced and overlapped segments of recorded or displayed imagery of scenes or objects. For some embodiments the media of display can be photographic prints or transparencies. For others the input imagery can be generated by computer, or by other electronic means, and displayed on some type of electronic display media. In particular, these displays can be of TV imagery. This array of input image segments is positioned on a surface in front of, and parallel to, the surface on which the arrays of lenses is mounted, and is separated from this surface by a distance less than the focal length of the lenses. For a particular embodiment, the displayed input image segments preferably have the same, or substantially the same, shapes and sizes as the lenses. Each displayed image segment is aligned with a lens behind it, and is a portion of the image of an entire scene or object. The portion of the entire image displayed on each segment is displaced laterally from those portions displayed on adjacent image segments by a distance which is dependent on the separation of the lens centres, the magnification of the lenses, the curvature of the surface on which the displayed image segments are positioned, and the relative angular orientation of adjacent facets of a multifaceted surface. For some embodiments, additional arrays of displayed input image segments are positioned on other surfaces, which are also parallel to the surface on which the array of lenses are positioned. The image segments in these additional arrays are formed from imagery of objects which were at different distances from the recording location. With careful positioning, virtual images of the displayed input image segments from a particular surface will be closely-matched together, so that an essentially seamless composite output image will be reconstructed on each of one or more surfaces in front of those on which the input image segments are located. Because they are located on surfaces at different distances from the lenses, these various images will exhibit parallax. The images can be viewed by one or more persons when looking through the array of lenses, as though through a window. The illusion is created that three dimensional imagery is being viewed. This is a major novel feature of this invention.        Embodiments of the invention in which the centres of the lenses are tangent to and touch a surface which is planar or concave towards the viewers are suitable for viewing; panoramic scenes or large objects over a wide range of azimuthal and elevation viewing angles. Other embodiments, in which the surface touched by the centres of the lenses is convex towards the locations of viewers, are suitable for stereoscopically viewing images of an object as seen with different perspectives from various positions around the viewing surface formed by the array of lenses.