Challenges of Stereoscopic Motion Picture Photography
Hoch, Winton C, American Cinematographer
A great deal has been written about stereoscopic photography. This most fascinating field seems to be periodically rediscovered. The question is why? Since stereo photography is the subject, it is inevitably tied into the technology of-and interest in-photography and stereoscopy by individuals and/or groups, generally for either pleasure, science or business, or any combination of these. Money, technology and interest are essential ingredients.
Currently we are presented with a breakthrough in 3-D "photography" in the form of holograms. This development is, in many opinions (and also in mine), one of the more fascinating current scientific developments. Holograms are only a very small part of a laser technology that is developing with great strides. If we accept their limitations in "photography" or recording of the images, and the limitations of viewing, they have no equal at present. This is a superb technique!
The limitations require close examination. Holography uses very expensive, very sophisticated equipment and imposes severe restrictions on scope, subject matter, lighting techniques, etc. For instance lasers of any appreciable power necessary for even medium-size areas are hazardous.
Many intriguing demonstrations are available and many applications are of great value. However, the many inherent restrictions make it essentially unattainable and highly impractical for general motion picture applications.
In brief, holography appears not at all feasible for the type of motion picture applications that form more than 99% of our current operational pattern.
Accepting this conclusion, let us consider more flexible and much less restrictive depth-portraying techniques.
Depth cues are conveyed to the mind in several ways. A "flat" (non-stereo) two-dimensional picture can present a feeling of depth by several well-known techniques, such as: perspective, scaling, use of haze, etc. Motion picture photography has the added inherent advantage of a moving viewpoint when the camera is moved as in "dolly" shots and "running" shots. If there is no stationary foreground, these exceptional shots can, on occasion, approach stereoscopic viewing. The primary principle can be easily verified. Sit in a room with stationary objects at various distancesthe objects preferably overlapping their outlines and at least one close to you. Close one eye. The scene is "flat". All sense of depth is lost except that in your memory. Keep one eye closed and move your head side-ways. Immediately you have evaluated the depth of the scene and the distance of the various objects! A motion picture "running" shot gives similar information, such as a side-angle running shot or a forwardlooking shot (with a wide-angle lens) and projected onto a curugd, theatre screen. The roller coaster ride in "THIS IS CINERAMA" is an outstanding example.
While these exceptional flat" scenes can be effective in presenting depth on occasion, they cannot truly compete with bona fide stereo presentations. The only time I have ever seen an audience dodge a missile coming out of the screen was in a stereo presentation. Stereoscopy does have an overwhelming noncompetitive audience participation capability!
Therefore, accepting this stereo approach and using the time-tested tools of photography (or any other practical image recording technology), we are faced with the basic problem of taking the picture to the audience or of taking the audience to the picture. This is the classical premise.
If we take the picture to the audience we must photograph, record or otherwise "capture" a multiplicity of viewpoints with the effect that each member of the audience sees the picture oriented to his viewing position in the audience. This infers not only laterally displaced viewpoints, but also vertically displaced viewpoints. Let us assume a simplified version of just laterally displaced viewpoints. Even this simplified approach requires a multiplicity of images for both recording and reproducing (or photography and projection). …