Browsing by Subject "3DTV"

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Open Access
A aurvey of signal processing problems and tools in holographic three-dimensional television
(Institute of Electrical and Electronics Engineers, 2007) Onural, L.; Gotchev, A.; Özaktaş, Haldun M.; Stoykova, E.
Diffraction and holography are fertile areas for application of signal theory and processing. Recent work on 3DTV displays has posed particularly challenging signal processing problems. Various procedures to compute Rayleigh-Sommerfeld, Fresnel and Fraunhofer diffraction exist in the literature. Diffraction between parallel planes and tilted planes can be efficiently computed. Discretization and quantization of diffraction fields yield interesting theoretical and practical results, and allow efficient schemes compared to commonly used Nyquist sampling. The literature on computer-generated holography provides a good resource for holographic 3DTV related issues. Fast algorithms to compute Fourier, Walsh-Hadamard, fractional Fourier, linear canonical, Fresnel, and wavelet transforms, as well as optimization-based techniques such as best orthogonal basis, matching pursuit, basis pursuit etc., are especially relevant signal processing techniques for wave propagation, diffraction, holography, and related problems. Atomic decompositions, multiresolution techniques, Gabor functions, and Wigner distributions are among the signal processing techniques which have or may be applied to problems in optics. Research aimed at solving such problems at the intersection of wave optics and signal processing promises not only to facilitate the development of 3DTV systems, but also to contribute to fundamental advances in optics and signal processing theory.
Open Access
Current research activities on holographic video displays
(SPIE, 2010) Onural, Levent; Yaraş, Fahri; Kang, Hoonjong
"True 3D" display technologies target replication of physical volume light distributions. Holography is a promising true 3D technique. Widespread utilization of holographic 3D video displays is hindered by current technological limits; research activities are targeted to overcome such difficulties. Rising interest in 3D video in general, and current developments in holographic 3D video and underlying technologies increase the momentum of research activities in this field. Prototypes and recent satisfactory laboratory results indicate that holographic displays are strong candidates for future 3D displays.
Open Access
Digital holographic three-dimensional video displays
(IEEE, 2011-02-04) Onural, L.; Yaras, F.; Kang, H.
Holography aims to record and regenerate volume filling light fields to reproduce ghost-like 3-D images that are optically indistinguishable from their physical 3-D originals. Digital holographic video displays are pixelated devices on which digital holograms can be written at video rates. Spatial light modulators (SLMs) are used for such purposes in practice; even though it is desirable to have SLMs that can modulate both the phase and amplitude of the incident light at each pixel, usually amplitude-only or phase-only SLMs are available. Many laboratories have reported working prototypes using different designs. Size and resolution of the SLMs are quite demanding for satisfactory 3-D reconstructions. Space–bandwidth product (SBP) seems like a good metric for quality analysis. Even though moderate SBP is satisfactory for a stationary observer with no lateral or rotational motion, the required SBP quickly increases when such motion is allowed. Multi-SLM designs, especially over curved surfaces, relieve high bandwidth requirements, and therefore, are strong candidates for futuristic holographic video displays. Holograms are quite robust to noise and quantization. It is demonstrated that either laser or light-emitting diode (LED) illumination is feasible. Current research momentum is increasing with many exciting and encouraging results.
Open Access
An overview of the holographic display related tasks within the European 3DTV project
(SPIE, 2006) Onural, Levent; Özaktaş, Haldun M.; Stoykova, E.; Gotchev, A.; Watson J.
A European consortium has been working since September 2004 on all video-based technical aspects of three-dimensional television. The group has structured its technical activities under five technical committees focusing on capturing 3D live scenes, converting the captured scenes to an abstract 3D representations, transmitting the 3D visual information, displaying the 3D video, and processing of signals for the conversion of the abstract 3D video to signals needed to drive the display. The display of 3D video signals by holographic means is highly desirable. Synthesis of high-resolution computer generated holograms with high spatial frequency content, using fast algorithms, is crucial. Fresnel approximation with its fast implementations, fast superposition of zonelens terms, look-up tables using pre-computed holoprimitives are reported in the literature. Phase-retrieval methods are also under investigation. Successful solutions to this problem will benefit from proper utilization and adaptation of signal processing tools like waveletes, fresnelets, chirplets. and atomic decompositions and various optimization algorithms like matching pursuit or simulated annealing.
Open Access
Scene representation technologies for 3DTV-a survey
(Institute of Electrical and Electronics Engineers, 2007-11) Alatan, A. A.; Yemez, Y.; Güdükbay, Uğur; Zabulis, X.; Müller, K.; Erdem, C.; Weigel, C.; Smolic, A.
3-D scene representation is utilized during scene extraction, modeling, transmission and display stages of a 3DTV framework. To this end, different representation technologies are proposed to fulfill the requirements of 3DTV paradigm. Dense point-based methods are appropriate for free-view 3DTV applications, since they can generate novel views easily. As surface representations, polygonal meshes are quite popular due to their generality and current hardware support. Unfortunately, there is no inherent smoothness in their description and the resulting renderings may contain unrealistic artifacts. NURBS surfaces have embedded smoothness and efficient tools for editing and animation, but they are more suitable for synthetic content. Smooth subdivision surfaces, which offer a good compromise between polygonal meshes and NURBS surfaces, require sophisticated geometry modeling tools and are usually difficult to obtain. One recent trend in surface representation is point-based modeling which can meet most of the requirements of 3DTV, however the relevant state-of-the-art is not yet mature enough. On the other hand, volumetric representations encapsulate neighborhood information that is useful for the reconstruction of surfaces with their parallel implementations for multiview stereo algorithms. Apart from the representation of 3-D structure by different primitives, texturing of scenes is also essential for a realistic scene rendering. Image-based rendering techniques directly render novel views of a scene from the acquired images, since they do not require any explicit geometry or texture representation. 3-D human face and body modeling facilitate the realistic animation and rendering of human figures that is quite crucial for 3DTV that might demand real-time animation of human bodies. Physically based modeling and animation techniques produce impressive results, thus have potential for use in a 3DTV framework for modeling and animating dynamic scenes. As a concluding remark, it can be argued that 3-D scene and texture representation techniques are mature enough to serve and fulfill the requirements of 3-D extraction, transmission and display sides in a 3DTV scenario. © 2007 IEEE.
Open Access
Signal processing issues in diffraction and holographic 3DTV
(Elsevier BV, 2007) Onural, L.; Özaktaş, Haldun M.
Image capture and image display will most likely be decoupled in future 3DTV systems. Due to the need to convert abstract representations of 3D images to display driver signals, and to explicitly consider optical diffraction and propagation effects, it is expected that signal processing issues will be of fundamental importance in 3DTV systems. Since diffraction between two parallel planes can be represented as a 2D linear shift-invariant system, various signal processing techniques naturally play an important role. Diffraction between tilted planes can also be modeled as a relatively simple system, leading to efficient discrete computations. Two fundamental problems are digital computation of the optical field arising from a 3D object, and finding the driver signals for a given optical display device which will then generate a desired optical field in space. The discretization of optical signals leads to several interesting issues; for example, it is possible to violate the Nyquist rate while sampling, but still achieve full reconstruction. The fractional Fourier transform is another signal processing tool which finds applications in optical wave propagation.
Open Access
Signal processing problems and algorithms in display side of 3DTV
(IEEE, 2006-10) Ulusoy, E.; Esmer, Gökhan Bora; Özaktaş, Haldun M.; Onural, Levent; Gotchev, A.; Uzunov, V.
Two important signal processing problems in the display side of a holographic 3DTV are the computation of the diffraction field of a 3D object from its abstract representation, and determination of the best display configuration to synthesize some intended light distribution. To solve the former problem, we worked on the computation of ID diffraction patterns from discrete data distributed over 2D space. The problem is solved using matrix pseudo-inversion which dominates the computational complexity. Then, the light field synthesis problem by a deflectable mirror array device (DMAD) is posed as a constrained linear optimization problem. The formulation makes direct application of common optimization algorithms quite easy. The simulations indicate that developed methods are promising. ©2006 IEEE.
Open Access
Three-dimensional holographic video display systems using multiple spatial light modulators
(2011) Yaraş, Fahri
Spatial light modulators (SLMs) are commonly used in electro-holographic display systems. Liquid crystal on silicon, liquid crystal, mirror-based, acousto-optic and optically addressed devices are some of the SLM types. Most of the SLMs are digitally driven and pixelated; therefore, they are easy to use. We use phase-only SLMs in our experiments. Resolution and size of currently available SLMs are inadequate for satisfactory holographic reconstructions. Space-bandwidth product (SBP) is a good metric for the quality assessments. High SBP is needed when lateral or rotational motion is allowed for the observer. In our experiments 2D images whose sizes are even larger than the SLM size are reconstructed using single SLM holographic displays. Volume reconstructions are also obtained by using such displays. Either LED or laser illumination is used in our experiments. After the experiments with the single SLM holographic displays, some laboratory prototypes of multiple SLM holographic systems are designed and implemented. In a real-time color holographic display system, three SLMs are used for red, blue and green channels. GPU acceleration is also used to achieve video rates. Beam-splitters and micro-stages are used for the alignments in all multiple SLM designs. In another multiple SLM configuration, SLMs are tiled side by side to form a three by two matrix to increase both vertical and horizontal field of view. Larger field of view gives flexibility to the observer to move and rotate around the reconstructed images of objects. To further increase the field of view, SLMs are tiled in a circular configuration. A single large beamsplitter is used to tile the SLMs side by side without any gap. A cone mirror is used to direct incoming light toward all SLMs. Compared to planar configuration, circularly configured multiple SLMs increase the field of view, significantly. With the help of such configurations holographic videos of ghost-like 3D objects can be observed binocularly. Experimental results are satisfactory.