The Cine Technician (1953-1956)

122 THE CINE-TECHNICIAN June 1954 THODUCTION TO 3-D FILM by Raymond and Nigel Spottiswoode I^HIS is not a history of the 3-dimensional film ■ nor a manual of stereoscopic projection, nor a study of the aesthetics of a new art form: those things must wait for a later and longer book. The aim of these pages is at once narrower and more general: narrower in that we concentrate on a single problem, the transfer of a scene in the solid spatial world to a distant place where it is re-created in its original three dimensions; more general in that, until the physical and psychological laws of this transfer are properly understood, 3-dimensional films can no more be created consistently than could painting as we know it have come into being without a knowledge of the laws of perspective. When the term " stereoscopic " or one of its equivalents is used in this book, it must be taken in its accepted sense — that is, as denoting a method of transmission which calls into play those means of apprehending depth which result from the possession by human beings of two normal eyes. Thus the transfer of a scene in space by a storage medium such as film, and its re-creation elsewhere in space, as in a cinema, may be called stereoscopic transmission. It might be thought that this would present no great difficulty, since some form of optical image could be created in actual depth, which would furnish a simulacrum of reality and could be viewed " in the round " by any number of spectators just as if they were looking at a representation on a stage. This " total cinema," proposed by many quasi-scientific writers, raises technical difficulties which have so far proved insuperable; and, as we shall presently see, the kind of image which is contained within the four walls of the theatre is in many ways more limited and less aesthetically satisfying than that which is produced by the very much simpler techniques which alone are practicable today. These techniques are essentially synthetic: they involve the presentation separately to the two eyes of each spectator of disparate left and right views of the scene. Whereas individual viewing is possible with pictures mounted side by side, as in the stereoscope, the conditions of mass viewing on large screens demand that the pictures be superimposed. The problem then remains to separate the two views, or sets of views, which are destined for the two eyes of the spectator, since, were they to become exchanged or intermingled, a totally false effect of space would result. There is no difficulty in keeping the left and right-eye images separate through the long chain of film production which leads from the camera, through the laboratory and editing stages, to the projector. But how to ensure that, once launched into space toward the cinema screen, the two pictures do not become inextricably mingled, with the result that both eyes of all the spectators see both pictures, when there may be more than a thousand spectators in the theatre? This problem — that of stereoscopic separation — is for large audiences so difficult that it defied the ingenuity of inventors for more than fifty years, and is still far from a perfect solution. Though it falls outside the scope of this book, stereoscopic separation cannot be dismissed without a brief comment. The left and right-eye images, or groups of images, can be separated only at two places, the screen and the spectators' eyes. If at the screen, an infinite number of images must in principle be provided; if at the eyes, only two, but then each spectator must wear some kind of viewing device. At present there is only one practicable method of separation, that which employs polarised projection light and polarised viewers for the spectators. Though commercial film Extracted from " The Theory of Stereoscopic Transmission " by Raymond and Nigel Spottiswoode, the most authoritative work on the subject yet published. Part One of the book furnishes a general theory of the transmission of the space image; Part Two applies it to film production problems; Part Three to detailed camera, printing and projection processes. Part Four offers some evidence on the difference between the image geometrically constructed and the image psychologically received by the members of an audience. The book is published by Faber & Faber and costs %2/-.