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A realtime hardware system for stereoscopic videoconferencing with viewpoint adaptation 1 The work described herein was performed within the ACTS PANORAMA project, funded by the European Commission under grant AC092. 1
Abstract
This paper describes a hardware system and the underlying algorithms that were developed for realtime stereoscopic videoconferencing with viewpoint adaptation within the European PANORAMA project. The goal was to achieve a true telepresence illusion for the remote partners. For this purpose, intermediate views at arbitrary positions must be synthesized from the views of a stereoscopic camera system with rather large baseline. The actual viewpoint is adapted according to the head position of the viewer, such that the impression of motion parallax is produced. The whole system consists of a disparity estimator, stereoscopic MPEG-2 encoder, disparity encoder and multiplexer at the transmitter side, and a demultiplexer, disparity decoder, MPEG-2 decoder and interpolator with viewpoint adaptation at the receiver side. For transmission of the encoded signals, an ATM network is provided. In the final system, autostereoscopic displays will be used. The algorithms for disparity estimation, disparity encoding and disparity-driven intermediate viewpoint synthesis were specifically developed under the constraint of hardware feasibility.
We investigate the design of an interpolation filter of a MF-TDMA demodulator which is applied to DVB-RCS. If sampling is not synchronized to the data symbols, timing adjustment in digital receiver must be performed by interpolation. It is impossible that conventional sinc interpolation filter coefficients are actually extended to infinity. We propose a Kaiser window interpolation filter and a sinc interpolation filter using th Kaiser window. Simulation results show that the performance improvement is realized by employing the proposed interpolation filter.
This paper discusses an approach to 3D-Television that is based on the Layered Depth Video (LDV) format. The LDV format contains explicit depth and occlusion information, allowing for the generation of novel viewpoints for stereoscopic and auto-stereoscopic multi-view displays. Thus, the format is effectively invariant to the display type and also allows the depth impression to be easily changed to best meet viewers' preferences for visual comfort. The major aspects of a content delivery chain based on the LDV format are discussed in this paper. The requirements placed on data acquisition are introduced, and a multi-camera system, which is well suited for LDV compliant data capture, is presented. Also discussed is the conversion of different input data streams, like standard stereo videos, multi-view data supplemented by depth data, and videos from wide baseline setups, to the LDV format. Moreover, the advantages of the LDV format in editing and mixing are examined. The paper also presents a transmission system based on currently available coding and transmission standards. Optimization of the bandwidth via different approaches to the compression of the LDV signal is analyzed, and the results of conducted experiments in this field are discussed. Finally, the aspects of perceptual human factors for the proper evaluation of 3D-TV services and the implemented LDV system are examined. This contribution reflects the efforts of the EU-funded project 3D4YOU to unify all aspects of 3D-TV production.
The estimation of correspondences in natural image pairs plays an important role in a large number of applications such as video coding, frame rate conversion, multi-viewpoint image generation, camera calibration, 3D from stereo, and structure from motion. An overview of the techniques for dense geometric correspondence estimation is presented. Different types of image pairs are discussed. Some improvements for correspondence estimation in image pairs are projected, which include, the estimation of all pseudo-correspondences, the incorporation of image restoration models, modeling of specular reflectivity of scene surfaces, the use of image sequences, and the application of epipolar geometry.
This paper introduces a new form of representation for
three-dimensional (3-D) video objects. We have developed a technique to
extract disparity and texture data from video objects that are captured
simultaneously with multiple-camera configurations. For this purpose, we
derive an “area of interest” (AOI) for each of the camera
views, which represents an area on the video object's surface that is
best visible from this specific camera viewpoint. By combining all AOIs,
we obtain the video object plane as an unwrapped surface of a 3-D
object, containing all texture data visible from any of the cameras.
This texture surface can be encoded like any 2-D video object plane,
while the 3-D information is contained in the associated disparity map.
It is then possible to reconstruct different viewpoints from the texture
surface by simple disparity-based projection. The merits of the
technique are efficient multiview encoding of single video objects and
support for viewpoint adaptation functionality, which is desirable in
mixing natural and synthetic images. We have performed experiments with
the MPEG-4 video verification model, where the disparity map is encoded
by use of the tools provided for grayscale alpha data encoding. Due to
its simplicity, the technique is suitable for applications that require
real-time viewpoint adaptation toward video objects
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