Journal of the Society of Motion Picture and Television Engineers (1950-1954)

Hyperstereoscopy Hyperstereoscopy is the term applied when an interaxial base several times normal is used. It has often been employed in mountain photography and serves admirably to reveal distant details in relief. The base employed is often 100 yd or more. Care must be taken not to include any foreground, otherwise one image will contain elements not present in the other, and it will be impossible properly to fuse the stereogram. Since mountains can usually be depended upon to stand still for a long time, there is time to set up the camera and to transport it from one extreme of the interaxial base to the other. But clouds are not so considerate in "staying put" as mountains, so the exposures should be made on a cloudless day. Hyperstereograms, properly made, require that certain rules for determining the interaxial be followed. The simplest one is d X D D-d -T 50 I where d is the distance to the nearest object, D the distance to the farthest and 50 the divisor whose use assures success. Keeping within the limits prescribed will give the stereograms the most vivid relief possible without eyestrain in viewing. Hyperstereoscopy has been employed to make stereograms of bodies in the solar system where even the mean diameter of the earth often proves insufficient as an interaxial base. Stereograms of most planets have been made and interesting data has thus been obtained. Included has been the discovery of a planetoid, which was found as the result of this type of stereoscopic survey, and it was appropriately named Stereoscopia in tribute to the method. Stereograms of the moon have been made which reveal intimate details of its craters and seas. Some of the most remarkable have been those of Saturn and its rings, one pair of which required the movement of Earth through space that was the equivalent of an interaxial base of about 1 ,000,000 miles, which is the distance traversed by our planet in its orbit during a 24-hr period. Other stereograms of this planet made with an even greater base disclosed clearly the separation of its unusual rings one from another and from the planet. A word of warning concerning hyperstereoscopy : it does not seem to produce satisfactory results for close-up objects, and certainly will not do so if such stereograms are projected. This is so for close objects because the angle formed between the two lenses at the base and the object is so great that it throws distortion into the images. For instance, photographing a golf ball at a distance of one foot and using a wide interaxial will produce a stereogram which makes the golf ball appear egg shaped, and golf balls having this shape give neither the player nor the viewer any pleasure (Fig. 20). High-speed stereoscopic photography is often employed for special purposes. Such stereograms often reveal things not readily apparent in a flat picture. They are particularly useful in the study of machine elements in motion and for other kinds of research. A series of three high-speed "strobe" shots were made for United States Rubber Company to prove the behavior of a golf ball. The illustrations show the impact of the club head, the "flattening-out" of the ball before leaving the tee, and the ball in its flight a few inches ahead of the club. These shots were made on Ektachrome film at a speed of one-millionth of a second, using one of Prof. Harold E. Edgerton's newer flash units. Prof. Edgerton and Henry Lester worked together in obtaining these shots. The projected pictures showed no "eggshape" distortion which would have resulted if an interaxial larger than called for by the object distance had been employed. No graphic means, besides the stereogram, can substitute for the re-creation J. A. Norling: The Stereoscopic Art — A Reprint 283