Survey of 3DTV Displays-Techniques and Technologies

Survey of 3DTV Displays-Techniques and Technologies



The display is the last component in a chain of activity from image acquisition, compression, coding transmission and reproduction of 3-D images through to the display itself. There are various schemes for 3-D display taxonomy; the basic categories adopted for this paper are: holography where the image is produced by wavefront reconstruction, volumetric where the image is produced within a volume of space and multiple image displays where two or more images are seen across the viewing field. In an ideal world a stereoscopic display would produce images in real time that exhibit all the characteristics of the original scene. This would require the wavefront to be reproduced accurately, but currently this can only be achieved using holographic techniques. Volumetric displays provide both vertical and horizontal parallax so that several viewers can see 3-D images that exhibit no accommodation/convergence rivalry. Multiple image displays fall within three fundamental types: holoform in which a large number of views give smooth motion parallax and hence a hologram-like appearance, multiview where a series of discrete views are presented across viewing field and binocular where only two views are presented in regions that may occupy fixed positions or follow viewers’ eye positions by employing head tracking. Holography enables 3-D scenes to be encoded into an interference pattern, however, this places constraints on the display resolution necessary to reconstruct a scene. Although holography may ultimately offer the solution for 3DTV, the problem of capturing naturally lit scenes will first have to be solved and holography is unlikely to provide a short-term solution due to limitations in current enabling technologies. Liquid crystal, digital micromirror, optically addressed liquid crystal and acoustooptic spatial light modulators (SLMs) have been employed as suitable spatial light modulation devices in holography. Liquid crystal SLMs are generally favored owing to the commercial availability of high fill factor, high resolution addressable devices. Volumetric displays provide Manuscript received March 8,2007; revised June 15,2007. This work was supported in part by EC within FP6 under Grant 511568 with the acronym 3DTV. both vertical and horizontal parallax and several viewers are able to see a 3-D image that exhibits no accommodation/convergence rivalry. However, the principal disadvantages of these displays are: the images are generally transparent, the hardware tends to be complex and non-Lambertian intensity distribution cannot be displayed. Multiple image displays take many forms and it is likely that one or more of these will provide the solution(s) for the first generation of 3DTV displays. THE DISPLAY is the last, but not the least, significant aspect in the development of 3DTV and vision. As has been outlined in other papers in this issue, there is a long chain of activity from image acquisition, compression, coding transmission and reproduction of 3-D images before we get to the display itself. The concept of a 3-D display has a long and varied history stretching back to the 3-D stereo photographs made in the late 19th century through 3-D movies in the 1950’s, holography in the 1960’s and 1970’s and the 3-D computer graphics and virtual reality of today. The need for 3-D displays and vision grows in importance by the day, as does the number of applications such as scientific visualization and measurement, medical imaging, telepresence, gaming, as well as movies and television itself. Many different methods of 3-D displays have manifest themselves over the last few decades, but none has yet been able to capture the mass market. Much of development in 3-D imaging and displays of the latter end of the 20th century was spurred on by the invention of holography, and this was the catalyst which led to some of the significant advances in autostereoscopic and volumetric methods, whereas, advances in techniques of virtual reality have helped to drive the computer and optics industries to produce better head mounted displays and other 3-D displays.

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