Eri Giannaka

A platform for virtual collaboration spaces and educational communities: the case of EVE

This paper presents the design, implementation and evaluation of EVE Community Prototype, which is an educational virtual community aiming to meet the requirements of a Virtual Collaboration Space and to support e-learning services. Furthermore, this paper describes the design and implementation of an integrated platform for Networked Virtual Environments, called EVE Platform, which supports the afore-mentioned educational community. This platform supports stable event sharing and creation of multi-user three dimensional (3D) places, H.323-based voice over IP services integrated in 3D spaces as well as multiple concurrent virtual worlds.

Using VR technology to support e-learning: the 3D virtual radiopharmacy laboratory

We present a virtual laboratory, which is designed and implemented in the framework of the VirRAD European project. This laboratory represents a 3D simulation of a radio-pharmacy laboratory, where learners, represented by 3D avatars, can experiment on radio-pharmacy equipment by carrying out specific learning scenarios. We describe the functionality provided by this laboratory, the motivation factors which led to its formation, the technological decisions that were made for the optimization of the system as well as the envisioned steps to be carried out.

Designing virtual spaces to support learning communities and e-collaboration

In this paper, we present the design principles for virtual spaces and two different tools as solutions for supporting e-collaboration and multi-user communication in Web-based learning communities. The first solution, called Virtual Conference, is designed and implemented in the framework of the VirRAD European project. It is a two-dimensional space where participants represented by their photos can use various e-collaboration tools. The second solution, called EVE Training Area, is a three-dimensional space where participants, represented by 3D humanoid avatars, can use a variety of e-collaboration tools. This paper describes the functionality provided by both tools, compares them, and proposes cases for exploiting each solution.

Building e-learning communities: the case of VirRAD

We discuss the development of virtual communities and especially e-learning communities. In particular, we are inspired by VirRAD European project, and we present the intermediate results that have raised from the definition of this virtual radiopharmacy community.

Distribution and partitioning techniques for NVEs: the case of EVE

The majority of the systems and platforms developed for supporting distributed virtual environments are based on the concept of distribution from the early beginning of their development. In this paper we present the migration to a distributed virtual environment from a traditional client-server architecture. In particular, this paper describes the case of EVE, a networked virtual environment originally aimed to support small-scale applications. EVE started as a standard client-multi server architecture, which could support multiple concurrent virtual worlds with a maximum number of seventeen simultaneous participants in each of these worlds. However, the need to support larger-scale applications revealed that the traditional architecture, upon which EVE was based, is insufficient to meet the needs of these applications, which are large both in the sense of virtual space and graphics and in regard to the number of concurrent participants. This paper discusses the migration of EVE to a distributed platform, which is able to support large-scale networked virtual environments. In particular, the paper describes the modifications realized in the architectural model of the initial platform for supporting effectively large-scale applications. The basic entities of the distributed model are presented, their operations, as well as the interconnection among them. In addition, the paper presents an initial approach of the algorithm that is adopted for the efficient partitioning of the virtual world and the assignment of the clients to the entities and resources of the distributed platform. The approach presented is space-object driven, in the sense that both the actual size of the virtual space along with the number of objects with which the user can interact is taken into account during the partitioning

Performance improvement of Distributed Virtual Environments by exploiting objects’ attributes

Distributed virtual environments need to address issues related to the control of network traffic, resource management, and scalability. Given the distributed nature of these environments, the main problems they need to overcome are the efficient distribution of workload among the servers and the minimization of the communication cost. In this direction, a lot of work has been done and numerous relevant techniques and algorithms have been proposed. The majority of these approaches mainly focus on user entities and their interactions. However, most of actual DVE systems include additional and non-dynamic elements, denoted as objects, whose presence can affect users’ behavior. This paper introduces virtual objects’ attributes and proposes two approaches that exploit these attributes in order to handle workload assignment and communication cost in DVE systems. Both approaches take into account scenario-specific aspects of DVE systems, such as the impact that entities’ attributes have on each other and the way this impact can affect the system’s state. These scenario-specific aspects are then combined with quantitative factors of the system, such as workload, communication cost, and utilization. The experiments conducted in order to validate the behavior of the proposed approach show that the incorporation of object’s presence can improve the DVE system’s performance. More specifically, objects’ presence and their attributes can assist in the significant reduction in the communication cost along with effective workload distribution among the system’s servers.

A simulation modelling tool for Distributed Virtual Environments

Abstract Distributed Virtual Environments simulate the behaviour and activities of a great number of users interacting in a virtual world over a wide area network. The size of the virtual worlds and the tremendous number of users that these environments are called to support require additional bandwidth and computational resources. For supporting large-scale Distributed Virtual Environments, extended infrastructure is needed in terms of both hardware and software. However, both researchers and application designers do not always have access to such an extended infrastructure and the assessment and evaluation of developed performance improvement techniques becomes extremely difficult. To address this issue, this paper presents a simulation modelling tool, called STEADiVE for networked servers Distributed Virtual Environments that could be used by designers for evaluating the performance of their approaches under different scenarios and system settings. The validation of the simulation modelling tool has showed that it achieves high accuracy in representing a real DVE system. STEADiVE comes to fill in the gap in the area of simulation tools for these systems.

An Object Driven Partitioning Approach for Distributed Virtual Environments

Distributed virtual environments tend to become a de facto solution for large-scale networked virtual environments. One of the key issues and problems that need to be handled in the design of a scalable and effective distributed virtual environment system is the partitioning problem, which refers to the efficient assignment of the systems workload to the available resources of the system. This paper presents an object driven partitioning approach based on the partitioning algorithm of Lui & Chan, who proposed a three step technique for balancing the workload among the servers of the Distributed Virtual Environment.

Monitoring and Analyzing Performance of Networked Virtual Environments: The Case of EVE

This paper focuses on the performance monitoring of a networked virtual environment, called EVE, in order to identify the elements that degrade its network performance. In particular, based both on the architectural and communication model that EVE adopts in order to cope with the dynamic behavior of the network, we performed a series of experiments, taking into account the number of the connected users, the network load as well as the connection type of the users.

Networked Virtual Environments

The inherent need of humans to communicate acted as the moving force for the formation, expansion and wide adoption of the Internet. The need for communication and collaboration from distance resulted in the evolution of the primitive services originally offered (i.e., e-mail) to advanced applications, which offer a high sense of realism to the user, forming a reality, the so-called virtual reality. Even though virtual environments were first introduced as stand alone applications, which could run on a single computer, the promising functionalities of this new form of representation and interaction as well as the familiarity of the users with it drew increased research interest. This fact resulted in virtual reality to be viewed as the solution for achieving communication and collaboration between scattered users, in various areas of interest, such as entertainment, learning, training, etc. This led to the creation of Networked Virtual Environments (NVEs). In particular, NVEs were first introduced in the 1980’s and the first areas that exploited the newborn technology were military and entertainment applications. In particular, the U.S Department of Defense played an important role to the direction of applications, protocols and architectures for this promising technology. In the 1990’s, where academic networks became a reality, NVEs drew increased academic research interest and a variety of applications and platforms were developed. In particular, the academic community has reinvented, extended, and documented what the Department of Defense has done. The evolution and the results extracted by research on this field were widely adopted from multiple areas of interest, with main representative the entertainment area. Since 2000, where virtual reality technology, processing power of computers and the network were significantly improved, a wide variety of systems, protocols and applications were developed. In particular, the familiarization the end users with the Internet and the promising advantages and opportunities of Virtual Reality contributed to currently view NVEs as an effective tool for supporting communication and collaboration of scattered users. Currently, the application areas of NVEs have been widely expanded and their use can be found at military and industrial team training, collaborative design and engineering, multiplayer games (Zyda, 2005), mobile entertainment, virtual shopping malls, online tradeshows and conferences, remote customer support, distance learning and training, science, arts, industry, etc. Summarizing, NVEs nowadays tend to consist a powerful tool for communication and collaboration, with applications ranging from entertainment and teleshopping to engineering and medicine. To this direction, in the recent years important active research on this topic in both academic and industrial research is taking place.