![]() The infinite viewpoint camera method for synthetic holographic stereogram printing was proposed, whose core idea was to transform the perspective images into parallax related images. MIT studied the problem of image distortions in HPO holographic stereograms and proposed two predistortion techniques, i.e., the infinite camera predistortion method and the perspective slicing predistortion method. ![]() When viewing the transfer hologram from different virtual pupil positions, different perspective images can be captured by human eyes, and the stereoscopic vision is formed (see Figure 1d). To separate the aperture pupil plane and the viewing plane, the master hologram ( H 1 plate) should be recopied to the transfer hologram (the H 2 plate) with the image hologram photographing method, i.e., there are double exposures in the two-step method (see Figure 1c). When viewing the master hologram, eyes should be close to the positions of aperture pupils (see Figure 1b). Full parallax perspective images of the scene are acquired under incoherent illumination, and Fresnel holograms of them are recorded in different hogels (holographic elements) successively (see Figure 1a). The production and reconstruction of the two-step method is shown in Figure 1. With the two-step method, we can achieve a real–virtual combined holographic stereogram, i.e., the reconstructed 3D scene is viewed inside or outside of the holographic recording medium. The problem will not occur in full parallax holographic stereograms. When the viewer is not located at the slit plane of the stereogram, there will be image distortions. The earliest synthetic holographic stereograms are horizontal-parallax-only (HPO) holographic stereograms. Synthetic holographic stereogram printing was first proposed by DeBitetto and promoted by King et al. Holographic fringe patterns are diffracted and propagated to the recording medium, interfered with by the reference beam, and reflection volume-type holograms can be achieved. In wavefront printing, the holograms are calculated by a computer, but the algorithm is different from that of holographic fringe printing. ![]() Thin transmission holograms, such as the Fresnel hologram, the rainbow hologram, the image hologram, and the holographic stereogram, can be achieved. In holographic fringe printing, interference patterns are calculated by the computer, displayed by the spatial light modulator (SLM) and printed on the holographic recording medium directly. During the reconstruction of holographic stereograms, stereoscopic vision occurs when different perspective images with parallax information is viewed, and the parallax is changing when eyes are moving. After being interfered with by the reference beam, the information of perspective images is stored in the holographic recording medium. In synthetic holographic stereogram printing, the 3D scene is reconstructed by sequential perspective images that are captured by a tracking camera or modeled by a computer with rendering techniques. Edge lines are drawn for each zone of the crystal, and the crystal drawing is then made by drawing necessary edges to outline faces.According to the different sources of interference patterns and different approaches of recording, holographic printing techniques can be categorized into three types: synthetic holographic stereogram printing, holographic fringe printing, and wavefront printing. A line parallel to this zone pole, called an edge line, is drawn from the net into the adjoining drawing area. Each zone has a zone pole whose direction on the stereogram is parallel to the edges in the zone. Next, appropriate zone circles and their diameters are drawn. Concurrently, all face poles are moved along their small circles by the same number of degrees and with the same sense of motion as the viewpoint. ![]() The stereogram is then held in position, and the viewpoint moved along the W radius to the center of the net. The stereogram is then rotated as necessary to place this mark on the W radius of the net. A standard stereogram is prepared with all faces plotted, and the desired viewpoint is marked. A wholly general method is presented to produce accurate drawings of any crystal in any orientation from a stereogram of the crystal. ![]()
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