Integral 3D imaging is getting much attention as one of the viable candidates for natural 3D display. Compared with other stereoscopic techniques, it provides more freedom of viewing and sense of naturalness with reduced eye fatigue. Recently several approaches on the projection integral imaging have been issued because of its merits for large size implementation. However, the use of a concave or convex lens array can cause problems of high cost and spherical aberration. To overcome these problems, we propose a novel scheme using multi-facet flat mirrors and demonstrate its feasibility. Instead of spherical mirrors in a flat surface, multi-facet mirrors which contacts with the tangential line of a curved surface function like elemental mirror component. Lights reflected from different facet of each mirrors give different viewing perspectives. By using electronic capturing and display devices, the proposed method makes it possible to record and reconstruct 3D scene in real-time. In the experiment, only horizontal parallax is provided because one-dimensional surface can be made more easily. But extension for two-dimensional or computer generation of elemental images can be also done. Some detailed discussions on the design parameters will be shown in the presentation.
In stereoscopic or multiview 3-D display systems, the synthesis of intermediate sequences is essential to assure lookaround capability and continuous motion parallax so that it can enhance comfortable 3-D perception. The quadtree-based disparity estimation is one of the most popular methods for the synthesis of intermediate sequences, due to the simplicity of its algorithm and hardware implementation. We propose two solutions in order to reduce annoying flicker at object boundaries of synthesized intermediate sequences using quadtree-based disparity estimation. The first requires a new splitting scheme, providing more consistent quadtree splitting strategies during the disparity estimation. The second involves adaptive temporal smoothing, using the dissimilarity between the present frame and the previous one to reduce the error of disparity estimation. These two proposals are tested by using several stereoscopic sequences, and the results show that flicker is remarkably reduced by them.
A new optical architecture of multiview projection displays, based on mirrored light tunnel is presented. According to current concept, all perspective images should be arranged in line on the same projection panel. The light tunnel is made of two or more parallel plane mirrors, installed between the image projector and the screen. The mirrors are installed horizontally, close to the screen, being perpendicular to its surface. One of the perspective images is projected directly to the screen while the others experience reflection before they strike the screen. Vertical arrangement of the viewing zones is changed to horizontal with a help of slanted directional diffuser, incorporated in directional screen. The important features of new architecture is the usage of single projection lens and the absence of keystone distortion of projected perspective images.
A multi-view 3D video processor was designed and implemented with several FPGAs for real-time applications and a projection-type 3D display was introduced for low-cost commercialization. One high resolution projection panel and only one projection lens is capable of displaying multiview autostereoscopic images. It can cope with various arrangements of 3D camera systems (or pixel arrays) and resolutions of 3D displays. This system shows high 3-D image quality in terms of resolution, brightness, and contrast so it is well suited for the commercialization in the field of game and advertisement market.
In autostereoscopic imaging systems using lenticular, parallax barrier and integral photography plates as the viewing zone forming optics, the quality of the perceived image is different for different part of the viewing zone because of different view image mixing. The image quality is quantified by the number of different view images viewed simultaneously along the viewing axis. The image quality decreases as the viewing distance increases.
Characteristics and two building methods of diamond shaped pixel cell are introduced. It can provide wider horizontal direction size of viewing zone compared with its corresponding square or rectangular pixel cell and reduce the pseudoscopic effect. The two building methods are named as integer and non-integer depending on the number of different view pixels involved with the pixel cell. The full parallax images generated by these two methods shows that the integer method provides better image quality than the non-integer.
There are several ways of processing Images from multiview cameras for full parallax image generation. Among them, the most used one is laying the images as a rectangular shape pixel cell on the image display panel. However, it cannot maximize the stereoscopic effect and viewing zone size in horizontal direction with a given full parallax image set. A diamond shape pixel cells can maximize the stereoscopic effect and the viewing zone size in vertical direction. The sequence of making the diamond shape pixel cell includes two rotations of a multiview image with the rectangular pixel cell in opposite to each other with the same angle.
Auto-stereoscopic 21-inch display with eye tracking having wide viewing zone and bright image was fabricated. The image of display is projected to retinal through several optical components. We calculated optical system for wider viewing zone by using Inverse-Ray Trace Method. The viewing zone of first model is 155mm (theoretical value: 161mm). We could widen viewing zone by controlling paraxial radius of curvature of spherical mirror, the distance between lenses and so on. The viewing zone of second model is 208mm. We used two spherical mirrors to obtain twice brightness. We applied eye-tracking system to the display system. Eye recognition is based on neural network card based on ZICS technology. We fabricated Auto-stereoscopic 21-inch display with eye tracking. We measured viewing zone based on illumination area. The viewing zone was 206mm, which was close to theoretical value. We could get twice brightness also. We could see 3D image according to position without headgear.
Adopting a pixel cell plate designed by use of geometrical optics, a full parallax imaging is realized. The pixel cell plate is consisted of 2-dimensional array of pixel cells which are made of the same number pixels in each image of a N X N multiview image array.
A desktop 20 inches autostereoscopic display system based on two 6.5 inches LCD projection panels and a single objective is described. The system employs vertical separation of left and right views in the objective's entrance pupil for the viewing zone forming. The vertically separated views are horizontally divided with use of a positioned at the pupil. This diaphragm is composed of two horizontally parallel LC stripes shutters which are made of independently working 32 black and white LCD columns. A rear projection type screen made of a Fresnel lens with a vertical diffuser is used for the image projection. The screen provides the best viewing distance of 70 - 80 cm. The system equipped with a head-tracking device for 16-view image display. The system is compatible with any dual monitor SVGA video card with resolution 800 X 600 or any source of parallel stereoscopic video signal. The size of the system is comparable to that of 20 inch CRT monitor.
Based on joining viewing zones of two 8-view TV projection optics spatially without overlapping, a 16-view 3D imaging system is designed and its performances are demonstrated. Each 8-view TV projection optics projects different view images time sequentially and its operation is synchronized with the other. The system is performed well.
The problems related with a dichroic type polarization filter plate which is used as a spatial image separator for a non-glasses type stereoscopic display device utilizing a liquid crystal display panel are discussed. The filter plate is consisted of many parallel line filters. Each line filter is directing the light with the same polarization only to its corresponding pixel lines in the display panel. The filter plate is cemented to the display panel, back- illuminated by a halogen lamp through two cross-polarized polarizers in side by side. Two Fresnel lenses located before the filter plate for collimating the illuminating beam and after the liquid crystal display panel for forming the images of two polarizers in front of the liquid crystal display panel as viewing zones are used.