Optical Considerations in the Application of Holographic Stereomodels to Topographic Mapping

This paper describes a new method of holographically recording photogrammetric stereo-models. A twin projector system is used to form a stereomodel on a rear-projection screen. The two individual projections on the screen are recorded in a hologram independently by using two different reference beams. The holographic record of the stereomodel is viewed either through selective polarization of the reconstructing beams or through selective illumination of the hologram. A review of factors essential to the production of an accurate high resolution stereomodel indicates that "speckle" limits the resolution. For performing stereo presentation of photogrammetric data, holographic stereomodels have definite advantages over other types of synthesized 3-D holograms.