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A 3D tele-immersive system makes use of various technologies including imaging, multimedia, networking and telecommunication. This article discusses the design issues that should be considered in the networking parts of such systems and provides effective solutions to reduce the required communication bandwidth of an interactive session. The proposed technique is based on the use of motion estimation...
In this paper, we introduce a cheat-free path discovering process for peer-to-peer online games. The algorithm finds the requested path through the active participation of the users, but cheating is detected through a controller. The controller recalculates a path segment when two peers disagree in terms of cost, and identifies the cheater using the trust profile. This eventually lowers the computational...
In this paper we propose a new architecture based on Z-order curve and kd-tree that can efficiently handle issues related to update messages distribution to interested entities locations in a three-dimensional (3D) virtual environments where locations are described in terms of 3D coordinates. We also aim to minimize the number of routing hops in distribution of update messages, especially when updates...
Massively multiuser virtual environment (MMVE) applications have the challenge of update message exchange among a large number of users. Real-time collaboration in the virtual environments requires the updates to be exchanged with the minimum end-to-end latency and overhead. This article proposes a new clustering technique to improve the update message exchange efficiency in MMVE applications. The...
With the rapid development of applications in open distributed virtual environments, such as e-Business and virtual games, privacy is becoming a critical issue. This paper presents an intelligent agent-based framework for privacy payoff in virtual environments, with special focus on capability-based negotiation services. These services take into consideration users' entitlement to benefit from revealing...
Massively multi-user virtual environments (MMVE) incorporate computer graphics, sound and haptics to simulate the experience of real-time interaction among multiple users in a shared three-dimensional virtual world. Such applications therefore deal with the distribution of updates among their users to provide them with a common sense of time and place while interacting in the virtual environment....
Massively multi user virtual environment (MMVE) applications must deal with the challenge of update message exchange among a large set of nodes distributed over the Internet. Therefore design of scalable network protocols is a major concern in such large scale distributed architectures. Several approaches have been proposed to aid update exchange in MMVEs. Message localization has always been a key...
As Haptic devices become more affordable and economical, research in Haptic-based virtual rehabilitation systems is gaining more interest. In addition to the benefits provided by virtual rehabilitation, Haptics offer force and tactile feedback which can be crucial for many upper and lower extremity rehabilitation. In this paper, we present such a system that provides a rich media environment for motor...
Nowadays, stroke is one of the most frequent causes of severe adult disability in the world. Virtual reality and haptic technologies have emerged as promising assistive tools for effective diagnosis and rehabilitation intervention. The objective of this paper is to develop and test a set of five virtual exercises on top of a framework, which is designed for the diagnosis and rehabilitation of patients...
Haptic-based virtual rehabilitation systems have recently become a subject of interest. In addition to the benefits provided by virtual rehabilitation, they offer force and tactile feedback which can be crucial for many upper and lower extremity rehabilitation. In this paper, we present a system that uses haptics, in conjunction with virtual environments, to provide a rich media environment for motor...
Haptic-based virtual rehabilitation systems have recently become a subject of interest. In addition to the benefits provided by virtual rehabilitation, the haptic-based systems offer force and tactile feedback which can be for upper and lower extremity rehabilitation. In this paper, we present a system that uses haptics, in conjunction with virtual environments, to provide a rich media environment...
In this paper, we introduce a framework that supports a large number of participants in a collaborative virtual environment (CVE). We consider object classification based on avatars' physical characteristics to define the overlay network used to disseminate update messages between participants. This concept systematically puts objects into different logical clusters where each cluster can be rated...
Rehabilitation exercises supervised by occupational therapists (OTs), involve applying task-oriented forces to the injured/disabled area to regain, for instance, strength and range of motion. Haptic interfaces have shown clear benefits in imitating therapists' exercises with the possibilities of position, grasping angles and force capturing. In this paper, we present two haptic-based virtual reality...
Haptic-based hand rehabilitation exercises set in virtual environments have not focused on analyzing the data captured during exercises to draw conclusions that relate to specific aspects of the hand. The framework proposed in this study implemented virtual reality exercises carried out with the use of haptic devices for use in stroke rehabilitation. The exercises were tested with healthy subjects...
Simulation lag is a known issue in networked virtual environments where users are geographically distributed. When users collaborate across the network using haptics, there are always momentary lacks of synchronization due to packet delay, loss, and jitter. Many strategies exist for dealing with such scenarios, but these strategies concentrate on one aspect and don't adequately address the necessary...
The recovery of hand functions in post-stroke patients relies on the length of therapy that is available to them. Rehabilitation exercises supervised by occupational therapists are characterized by repetitiveness and a constant increase in intensity. However, due to resource limitations, facilities and time allocated to recovering stroke patients restrict the maximum level of rehabilitation that can...
One of the known problems with shared object manipulation in collaborative virtual environments (CVE) is the disruptive effect of network lag in collaboration sessions. It is widely recognized that delay and jitter cause significant problems for CVEs. Most solutions to this problem revolve around techniques to compensate for this lag at the networking level. More recently, the usage of visual cues...
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