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ABSTRACT: We discuss how numerical algorithms for digital holography (DH) may be improved by execution on parallel architecture. In particular we consider implementation on graphics hardware. As an example we present an algorithm for twin-image removal.
ICO Topical Meeting on Optoinformatics / Information Photonics, St. Petersburg, Russia; 09/2008
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ABSTRACT: We propose and investigate a new digital method for the reduction of twin-image noise from digital Fresnel holograms. For the case of in-line Fresnel holography the unwanted twin is present as a highly corruptive noise when the object image is numerically reconstructed. We propose to firstly reconstruct the unwanted twin-image when it is in-focus and in this plane we calculate a segmentation mask that borders this in focus image. The twin-image is then segmented and removed by simple spatial filtering. The resulting digital wavefield is the inverse propagated to the desired object image plane. The image is free of the twin-image resulting in improved quality reconstructions. We demonstrate the segmentation and removal of the unwanted twin-image from in-line digital holograms containing real-world macroscopic objects. We offer suggestions for its rapid computational implementation.
Proceedings of SPIE, San Diego, CA, USA; 08/2008
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ABSTRACT: We present a method to analytically compute the light distribution of triangles directly in frequency space. This allows for fast evaluation, shading, and propagation of light from 3D mesh objects using angular spectrum methods. The algorithm complexity is only dependent on the hologram resolution and the polygon count of the 3D model. In contrast to other polygon based computer generated holography methods we do not need to perform a Fourier transform per surface. The theory behind the approach is derived, and a suitable algorithm to compute a digital hologram from a general triangle mesh is presented. We review some first results rendered on a spatial-light-modulator-based display by our proof-of-concept software.
Applied Optics 05/2008; 47(10):1567-74. · 1.41 Impact Factor
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ABSTRACT: We present a parallel implementation of the Fresnel transform suitable for reconstructing large digital holograms. Our method has a small memory footprint and utilizes the spare resources of a distributed set of desktop PCs connected by a network. We show how we parallelize the Fresnel transform and discuss how it is constrained by computer and communication resources. Finally, we demonstrate how a 4.3 gigapixel digital hologram can be reconstructed and how the efficiency of the method changes for different memory and processor configurations.
Optics Express 03/2008; 16(3):1990-5. · 3.59 Impact Factor
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ABSTRACT: This paper presents a novel method for using programmable graphics hardware to generate fringe patterns for SLM-based holographic displays. The algorithm is designed to take the programming constraints imposed by the graphics hardware pipeline model into consideration, and scales linearly with the number of object points. In contrast to previous methods we do not have to use the Fresnel approximation. The technique can also be used on several graphics processors in parallel for further optimization. We achieve real-time frame rates for objects consisting of a few hundred points at a resolution of 960x600 pixels and over 10 frames per second for 1000 points.
Optics Express 09/2006; 14(17):7636-41. · 3.59 Impact Factor
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ABSTRACT: We present a portable system to record synchronised, multi-video data for vision applications such as 3D reconstruction and video-based rendering of dynamic scenes. The aim of the project is to gain access to a greater number of scenes than what a static, wired indoor studio allows for. The portable acquisition system is constructed from a number of independent modules, each consisting of a FireWire camera and a laptop. Our software utilises wireless networking making the system behave like a tightly coupled unit without requiring the modules to be physically connected to each other. The scheme also includes an external calibration method suitable for general scenes. The system is scalable and allows for easy transportation and adhoc setup and configuration. We present recent results acquired in the field and their use for free-viewpoint video.
03/2004;
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ABSTRACT: We present a method for external camera calibration that is simple to use and o#ers generality in the positioning of the cameras. This makes it very suitable for the calibration of mobile, synchronized camera setups. We use a camera graph to perform global registration which helps lifting restrictions on the camera setup imposed by other calibration methods. A further advantage is that all information is taken into account simultaneously. The method is based on a virtual calibration object which is constructed over time by tracking an easily identifiable object through three-dimensional space. This implies that no calibration object must be visible simultaneously in all cameras.
02/2004;
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IEEE/OSA Journal of Display Technology.
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Cohen Or, Danny; Slavik, Pavel: Computer Graphics Forum, Blackwell Publishing, 435-446 (2007).
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ABSTRACT: \begin{abstract} Lately, new methods for the acquisition of time-varying, volumetric data for photo-realistic rendering of semi-transparent, volumetric phenomena like fire and smoke have been developed. This paper presents a wavelet-coding and rendering approach for these volumetric sequences that exploits spatial as well as temporal coherence in the data. A space partitioning tree allows for efficient storage and real-time rendering of dynamic, volumetric data on common PC hardware. \end{abstract}
Gröller, Eduard; Fujishiro, I.; Müller, Klaus; Ertl, T.: Volume graphics 2005 : Eurographics/IEEE VGTC workshop proceedings ; Fourth International Workshop on Volume Graphics, Eurographics, 83-90 (2005).
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ABSTRACT: This paper presents a light field rendering framework based on matrix optics. Matrix optics, in contrast to intersection-based methods such as ray-tracing, has the advantage that a generic series of optic operators can be combined into a single matrix. This enables us to realize a ``virtual optical bench'' where different setups can be easily tested. We introduce the theoretical foundation of matrix optics and define a set of operators suitable for light fields. We then discuss a wavelet compression scheme for our light field representation. Finally we introduce a real-time rendering approach based on matrix optics suitable for both uncompressed and compressed light fields.
Journal of WSCG, v.14, 177-184 (2006).
