In this paper, we propose an efficient framework for edge-preserving stereo matching. Local methods for stereo matching are more suitable than global methods for real-time applications. Moreover, we can obtain accurate depth maps by using edge-preserving filter for the cost aggregation process in local stereo matching. The computational cost is high, since we must perform the filter for every number of disparity ranges if the order of the edge-preserving filter is constant time. Therefore, we propose an efficient iterative framework which propagates edge-awareness by using single time edge preserving filtering. In our framework, box filtering is used for the cost aggregation, and then the edge-preserving filtering is once used for refinement of the obtained depth map from the box aggregation. After that, we iteratively estimate a new depth map by local stereo matching which utilizes the previous result of the depth map for feedback of the matching cost. Note that the kernel size of the box filter is varied as coarse-to-fine manner at each iteration. Experimental results show that small and large areas of incorrect regions are gradually corrected. Finally, the accuracy of the depth map estimated by our framework is comparable to the state-of-the-art of stereo matching methods with global optimization methods. Moreover, the computational time of our method is faster than the optimization based method.
In this paper, we propose a generalized framework of cost volume refinement filtering for visual corresponding problems. When we estimate a visual correspondence map, e.g., depth map, optical flow, segmentation and so on, the estimated map often contains a number of noises and blurs. One of the solutions for this problem is post filtering. Edge-preserving filtering, such as joint bilateral filtering, can remove the noises, but it causes blurs on object boundaries at the same time. As an approach to remove noises without blurring, there is cost volume refinement filtering (CVRF) that is an effective solution for the refinement of such labeling of correspondence problems. There are some papers that propose several methods categorized into CVRF for various applications. These methods use various reconstructing metrics functions, which are L1 norm, L2 norm or exponential function, and various edge-preserving filters, which are joint bilateral filtering, guided image filtering and so on. In this paper, we generalize these factors and add range-spacial domain resizing factor for CVRF. Experimental results show that our generalized formulation outperform the conventional approaches, and also show what the format of CVRF is appropriate for various applications of stereo matching and optical flow estimation.
This paper deals with two kinds of work in which two users manipulate different haptic interface devices from
each other. Although a number of haptic interface devices are currently available, the devices have different
specifications from each other. By experiment, we investigate the influences of difference in workspace size
between two devices (PHANToM Omni and PHANToM Desktop) on the efficiency of networked collaborative
work and the outcome of networked competitive work (i.e., a networked real-time game).
This paper deals with a remote haptic painting lesson system by which a teacher trains a student how to paint pictures or figures while conveying the sense of force interactively through a network. In the system, we introduce media synchronization control in order to achieve a high quality of haptic transmission. We make a quality
comparison of four media synchronization schemes (Virtual-Time Rendering (VTR), VTR with prediction, fixed buffering with prediction, and Skipping) by subjective assessment.
This paper examines the influences of network latency and packet loss on the playback quality of MPEG video on
iSCSI disks. The paper also explains the relationships between the video-playback quality and the transmission
speed, average bit rate of video, file-reading block size, and receive window (RWIN) size. Experimental results
indicate that the additional delay at which the average MU rate suddenly falls down increases as the RWIN size
becomes larger up to the amount of read-response data plus the number of bytes of the iSCSI response header.
In addition, we can reduce the deterioration in the video-playback quality by enlarging the file-reading block size.
This paper proposes a group (or inter-destination) synchronization scheme with prediction for haptic media in
a remote drawing system. The scheme aims to improve the group synchronization control, which adjusts the
output timing among multiple destinations, to keep the interactivity high. It outputs the position information by
predicting the future position later than received position information by a fixed amount of time. It also advances
the output time of position information at the local terminal by the same amount of time. By experiment, we
demonstrate the effectiveness of the scheme.
This paper presents an efficient approach for supporting wireless video full interactive services. One of the main goals
of wireless video multicast services is to provide priority including dedicated bandwidth, controlled jitter (required by
some real-time and interactive traffic), and improved loss characteristics. The proposed method is based on storing
multiple differently encoded versions of the normal/interactive video streams at the server. The corresponding video
streams are obtained by encoding the original uncompressed video file as a sequence of I-P(I) frames and I-P(M) frames
using different GOP (Group Of Pictures) pattern. Mechanisms for controlling the normal/interactive request are also
presented and their effectiveness is assessed through extensive simulations. Wireless normal/interactive video services
are supported with considerably reduced additional delay and acceptable visual quality at the wireless client-end.
This paper proposes an adaptive switching control scheme which dynamically switches between high-bit rate and
low-bit rate video files according to the network load for the playback of MPEG video stored on iSCSI disks.
The scheme adaptively switches read requests between the two video files by estimating the throughput from the
size of transmitted video data and the transmission time. By subjective assessment and objective assessment, we demonstrate the effectiveness of the scheme.
This paper assesses the media synchronization quality of preventive control schemes employed at media sources
and media destinations for voice and video over a network. Preventive control is required to try to avoid
asynchrony (i.e., out of synchronization). We here deal with two preventive control techniques employed at
sources: Advancement of transmission timing of media units (MUs), each of which is the information unit for
media synchronization (e.g., a video picture), with network delay estimation and temporal resolution control
of video. We also handle three preventive control techniques employed at destinations: Change of buffering
time with network delay estimation, preventive pausing, and preventive shortening of output duration. By
experiment, we make a performance comparison among preventive control schemes which employ the preventive
control techniques at sources and destinations. We also clarify the relations between subjective and objective assessment results.
This paper assesses the media synchronization quality of preventive control schemes employed at sources for stored video and voice over a network. The preventive control techniques are required to try to avoid asynchrony (i.e., out of synchronization). We here deal with two preventive control techniques employed at sources: Advancement of transmission timing of media units (MUs) with network delay estimation and temporal resolution control of video. By experiment, we make a performance comparison among preventive control schemes which employ one or two of the preventive control techniques. Experimental results show that a scheme which exerts the advancement of transmission timing together with the temporal resolution control is the most effective in terms of the media synchronization quality.
This paper deals with a system which conveys the haptic sensation experimented by a user to a remote user. In the
system, the user controls a haptic interface device with another remote haptic interface device while watching
video. Haptic media and video of a real object which the user is touching are transmitted to another user.
By subjective assessment, we investigate the allowable range and imperceptible range of synchronization error
between haptic media and video. We employ four real objects and ask each subject whether the synchronization
error is perceived or not for each object in the assessment. Assessment results show that we can more easily
perceive the synchronization error in the case of haptic media ahead of video than in the case of the haptic media
behind the video.
This paper deals with a remote control system which controls a haptic interface device with another remote haptic interface device. Applications of the system include a remote drawing instruction system, a remote calligraphy system and a remote medical operation system. This paper examines the influence of network latency on the output quality of haptic media by subjective assessment in the remote drawing instruction system. As a result, we show that the instructor has smaller Mean Opinion Score (MOS) values than the learner, and the MOS value can be estimated with high accuracy from the summation of the network latency from an instructor's terminal to a learner's terminal and that in the opposite direction.
KEYWORDS: Information visualization, Video, Visualization, Telecommunications, Data storage, Switches, Multimedia, Image compression, Switching, Local area networks
Advanced visual information retrieval systems supporting both video and images need to have flexible system design so that their system configurations can easily be enhanced. It is therefore desirable to separate the features of a central system into three parts: storage servers, communication servers, and a back-end network that combines these. In this architecture, unscheduled arrivals of data blocks at a back-end network cause two problems: unacceptable fluctuation of video frames and overly long delays of image transfer. To solve these problems, we have designed a new multimedia integrated switching system (MISS) that uses a fully connected crossbar switch to combine servers. MISS treats a time interval of a few hundred microseconds (called a `time-slot') as the basic unit of data block transfer, and allocates appropriate time-slots to all transfer requests in order to simultaneously meet the requirements for each kind of visual information transfer. According to simulation results and estimates based on queuing theory, MISS greatly reduces video frame fluctuation and halves the average image transfer delay. These effects have been confirmed in an experimental visual communication system built around MISS. This system supports JPEG compressed video and images, and six terminals can simultaneously retrieve visual information through an FDDI network.
KEYWORDS: Data communications, Control systems, Data storage, Telecommunications, Very large scale integration, Vestigial sideband modulation, Broadband telecommunications, Network architectures, Process control, Magnetism
A high-speed hardware architecture for an experimental
high-definition videotex system for a broadband integrated services digital network is introduced. The key technologies required are high-speed protocol processing, high-speed data transfer, and highspeed
picture readout from disks. High-speed protocol processing using a newly developed virtual memory copy, content rearrangement memory, two-bus architecture, and simultaneous editing and analyzing allows a requested 6-MB picture to be displayed within 3s.
KEYWORDS: Visual communications, Data communications, Telecommunications, Image processing, Data storage, Vestigial sideband modulation, Signal processing, Control systems, Process control, Magnetism
An experimental high-definition videotex system for broadband ISDN has been developed, and this paper introduces high-speed hardware architecture for this system. Key technologies required are highspeed protocol processing, high-speed data transfer, and high-speed picture readout. High-speed protocol processing — using a newly developed virtual memory copy, contents rearrangement memory, two-bus architecture, and simultaneous editing and analyzing — allows a requested 6-MB picture to be displayed within 3 seconds.
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