Journal of the Society of Motion Picture Engineers (1930-1949)

Fig. lla. Construction of spherical "I" and "B" surfaces, nonuniform elements. "0" °2 Fig. lib. Spherical "I" and plane "B» surfaces. dimension arrangement necessary for any practical use is more complicated. The above analysis is based upon a 100% utilization of available image area. It may be desirable to have both fixed surfaces of given shapes and a uniform pattern on one of the surfaces. This can be done, but only by sacrificing some of the image area. For example, the surface I can be chosen as spherical, and the barrier surface as a plane with a uniform dot pattern. This can be done if the aperture size in the plane barrier is small enough to avoid overlapping patterns on surface I. The Radial-Type Barrier. If the image, barrier and source surfaces are planar, they need not be parallel. The above principles can be used to generate nonparallel arrangements. One such arrangement of interest is the radial plane arrangement, invented by Ivanof and used for stereoscopic pictures. As shown in Fig. 12, all three planes meet in a common line of intersection and all band patterns of I, B and O planes converge toward a single point on this common line of intersection. For motion pictures — the I plane comprises the screen; the B plane, the parallax barrier; and the audience, the O plane. This arrangement permits a large number of seats to satisfy the parallax condition, in contrast to the parallel plane arrangement where only one row in the theater can meet the necessary condition. Of course, if the rows could be stacked vertically instead of horizontally then the parallel plane arrangement would be suitable. The Venetian-Blind Barrier. Instead of a separate barrier plane, the surface itself can be shaped to provide the 18 July 1952 Journal of the SMPTE Vol. 59