On aspects of glasses-free 3D cinema 70 years ago
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In the following pages attention focuses on four exemplar strands of pioneering research carried out in the first half of the twentieth century in designing and implementing glasses-free (autostereoscopic) 3D cinema. For nearly 100 years, it has been understood that stereoscopic techniques fundamentally based on conventional parallax barrier and lenticular methodologies are able to support multi-viewer glasses-free 3D – provided that all viewers are positioned at approximately the same distance from the screen. However, any approach that is to be successfully applied to cinema must clearly accommodate 3D viewing across the length and breadth of an auditorium. Central to the research efforts outlined in this document are innovative techniques which were intended to support this requirement. The most rapid advances in early glasses-free 3D cinema and 3D cinematography in general occurred in Russia, and by 1941 Moscow cinema-goers were able to experience 3D on a screen measuring ~5m by 3m - without recourse to viewing glasses. Despite there being fewer than 400 seats, in a four month period (i.e. up until Russia’s entry into WWII), approximately 500,000 people took the opportunity to view 3D – glasses-free. Three of the exemplar strands of research outlined here focus on work undertaken by Professor Edmond Noaillon in Belgium, Semyon Ivanov et al in Russia and François Savoye in France. In each case their glasses-free 3D cinema solutions utilised some form of ‘radial raster’ (in barrier and/or lenticular forms). Whilst Noaillon (the largely unrecognized inventor of this barrier geometry) focused on turning theory into practice via increasingly complex electromechanical techniques, Ivanov and co-workers adopted more pragmatic solutions. Further, shortly after the end of WWII they made the significant advance of replacing the radial barrier with a radial lenticular arrangement. As a result, autostereoscopic cinema soon flourished in a number of Russian cities. In parallel, following Savoye’s invention of the Cyclostereoscope, French audiences were quick to sample glasses-free 3D. Although Dennis Gabor is widely recognized for his work in the late 1940’s concerning the invention of holography, his extensive and innovative efforts in developing viable forms of glasses-free 3D cinema have received little attention. This work forms the fourth strand of pioneering activity selected for inclusion here. Discussion is limited to aspects of two patents filed by Gabor in 1940 in which images recorded on lenticular film are projected onto multi-layer optical structures. Related patents filed by Gabor in the 1960’s will be discussed in greater depth in other sections of the second volume of ‘3D Displays and Spatial Interaction’. There are many excellent publications devoted to the history of cinema. Early work undertaken in developing and deploying glasses-free 3D solutions has however received relatively little in-depth attention. This document is intended to provide a technology-centric insight into several indicative approaches – these are considered in an accessible trans-disciplinary framework. Given the cyclic nature of 3D research coupled with the emergence of new materials, processes and technologies, an appreciation of past work can help in the identification of techniques which may be applied to the development of the diverse forms of 3D tableau needed to satisfy today’s increasingly complex visualization requirements. However in parallel and from the perspective of planning future investment, it is important to recognize that in the case of some applications (particularly those involving the visualization of complex data sets and/or high levels of interaction), support for binocular parallax based 3D is in itself only a partial solution - natural support for motion parallax may be of at least equal importance.