| 摘要 |
1,178,298. Cathode-ray tube displays. INTERNATIONAL BUSINESS MACHINES CORP. 6 March, 1967 [11 July, 1966], No. 10382/67. Heading H4T. In an arrangement for producing a stereoscopic display of an image element the three co-ordinates of which are supplied from a data source, the spacing of the stereoscopic pair of image elements in the display is determined by the "depth perspective ratio", i.e. the ratio of the distance normal to the display surface of an effective viewing point to the sum of this distance plus the distance normal to the display surface of the "in space" position of the element the position of the image points being additionally controlled by perspective control means to enable a perspective view from various directions to be obtained. The display may be on a paper surface, a projection screen or the screen of a cathode-ray tube. In the case of the latter a single or double beam tube may be employed or two separate tubes, one for each eye view, may be employed. The described embodiment of the invention utilizes a single beam tube. Referring to Fig. 1, which shows a front view of the display surface in the X, Y plane and a side view in Z plane, the points NL and NR termed respectively, the left and right "vanishing points" represent the orthogonal projections of the left and right viewing points (e.g. VP repesents the right viewing point) on the display surface, the points L and R represent the stereoscopic pair images of the element D (having co-ordinates X, Y and Z) and the distance G, termed the "line of sight distance", is the distance from the "vanishing points" to the orthogonal projection of the element on the display surface. Utilizing the geometrical considerations shown circuits means (Fig. 2, not shown) supplied with the X, Y and Z co-ordinates of the element D derives deflection signals to position the display tube beam at the stereoscopic pair points L, R. The effective eye base K, which may have any value, since an optical viewing device is utilized to separate the left and right eye views and to convert the effective eye base to the approximate actual eye base of the observer, may be varied by perspective control means which varies the X and Y co-ordinates of the left "vanishing point" NL, the point NR being fixed, to enable the display to be viewed from other perspective positions. Additionally, means are provided for producing the effect of "zooming" by adding or subtracting a constant to the Z co-ordinate of the data and/or producing "depth exaggeration" by multiplying the Z co-ordinate by a constant. The X and Y co-ordinates of the stereoscopic pair points L, R for a succession of elements are first assembled and then cyclically supplied to the tube deflection means together with a bright-up pulse to produce a visible spot of short duration when the beam has been positioned at the required L and R points. The optical viewing device may utilize polarized or coloured light filters or other known devices to separate the left and right views. |
