یادگیری الکترونیکی از طریق محیط های مجازی توزیع شده

e-learning is one of the emerging needs of the information age. Access to education is going to become crucial for the success of our information society, and therefore a lot of potential is seen in distance learning and distributed virtual environments. The communicative character of the distributed virtual environments would allow students and staff to meet in social shared spaces and engage in on-line real-time seminars and tutorials. Such technologies may mitigate some of the problems of isolation that distance learning brings. This paper presents our work in multi-user distributed virtual environments which are designed and implemented for educational uses in the bounds of the VES project. Furthermore, it presents our proposal for the extensions and reconstruction of the current system in order to create a more efficient system, which can be characterized as a learning virtual environment.

On the one hand, e-learning technologies aim to accomplish the needs of an educational community, where participants (teacher, students and administrators) can exploit learning and communication capabilities. On the other hand, Virtual Environments (VEs) provide a way to combine the best features of real-world information navigation—memory of places and visual cues—with the best features of online navigation—fast searches and sorting and quick cross-referencing. Networked VEs can contribute to e-learning, offering additional functionality and capabilities to the users. There are many types of networked VEs that can be used in e-learning which are presented in the following paragraphs (Fig. 1). 1.1 Types of networked VEs 1.1.1 Multi-user distributed virtual environments (mDVEs). mDVEs allow a group of geographically separated users to interact in real time [1,2]. While a simple virtual environment is a computer-generated simulation with which the user can interact in such a way that he receives real time feedback [3],aiming to provide its users with a sense of realism, an mDVE is something more. In an mDVE, multiple users can interact with each other in real time,and furthermore the VE is distributed, running on several computers which are connected by a network using a series of client server applications [2,4]. mDVEs have many characteristics that can be exploited in the educational process and especially in distance learning. Specifically, mDVEs offer a way of communication and they give a shared sense of space, presence and time [5]. In addition, an mDVE application can meet the requirements for a complete Computer Mediated Communication (CMC) system [6], such as an easy to use interface, cross platform, conversation logs, indication of the presence of the attendees and multi-modal interaction. 1.1.2 Collaborative VE-systems (CVEs). An extension of an mDVE would be a CVE, which is an mDVE aimed at a collaborative task. CVEs aim to provide an integrated, explicit and persistent context for co-operation that combines both the participants and their information into a common display space. These objectives create the potential to support a broad range of co operative applications such as training [7]. 1.1.3 Learning virtual environments (LVEs). A simple definition of a Learning Virtual Environment (LVE) is a CVE aimed not only at a collaborative task but also at additional educational tasks such as synchronous and asynchronous learning. An LVE is a set of virtual worlds or a virtual world, which offers educational functionality to its users [8]. The avatars (the graphical representation)of these users populate the LVE and they are provided with additional behaviour such as gestures, interaction, movements and sound. 1.1.4 Immersive virtual environments. Immersive educational environments are supported by high-end equipment such as datagloves, Head Mounted Displays(HMD), ImmersaDesk and CAVE to visually immerse a user in the virtual world.These environments allow the users to interact in a shared environment and to have a more realistic experience rather than desktop virtual reality. Furthermore,there are systems that use the immersive technology along with live video displayed in the HMD instead of 3D graphics [7]. These systems constitute a telepresence system, which allows participants to experience a remote physical space through computer and communication technologies. According to an extended review on the educational uses of Virtual Reality(VR) technology [9], most of the educational VR applications do not support multiple users or do not provide any type of interaction between their users. More specifically, almost 2% of the current applications support multiple users with very limited types of interaction between users. Generally speaking, immersive applications are more effective in the use of VR technology. However, the main feature of educational VR applications is the interactivity and not the immersion. Moreover, a VR application, which is designed for educational use should be suitable for widespread use and mature in the part of the technology. Considering these requirements, immersive VR technology is not mature and it is expensive. On the other hand, desktop VR is more suitable for widespread use regarding the hardware and software requirements. In this paper, a threedimensional community is described which is implemented in the framework of the Virtual European School (VES) project [10,11]. 1.2 The virtual european school (VES) project VES is a European project in the educational multimedia sector, aiming to build up a comprehensive resource on teaching and learning material for secondary schools (pupils aged 10–19). The project started in March 1998 and ended in February 2000. Pedagogically, the VES project aims to reduce instructors’hesitation towards using computers as teaching assistants, by offering an innovative delivery system containing a large variety of material, supporting various pedagogical concepts. All material will be adapted specifically for school use by publishers possessing know-how of the educational sector. Additionally,VES aims to enable international social contact between pupils and teachers, providing communication tools, educational games and quizzes embedded in distributed virtual environments. Table 1 shows the participants of the consortium.The consortium is composed of partners from four countries (Austria, Greece,Italy and the United Kingdom), and school-networks within three countries(Austria, Greece, Italy). In each region, an organization performing and evaluation at content provider sites and schools is participating in the project. In this way, the user feedback loops are ensured. The technical system is set up by the Computer Technology Institute, Systema Informatics, and Joanneum Research. Evaluation of the system has been performed in all three regions, in parallel with teachers training. Scienter, an Italian organization, led this work. Further organizations with know-how in this field, and designing evaluation guidelines for schools are Call Austria, Lambrakis Research Foundation, and the Computer Technology Institute. The evaluation at publisher sites has been led by the Bundesgremium.There exist three user groups within the VES: publishers, teachers and pupils. Each of these groups is offered a user interface with special functionalities.Publishers are supported by tools in order to manipulate content in the database.Teachers are provided with an intelligent agent in order to search and compose lessons. Pupils can view the pre-selected material and will normally enter VES through a 3D interactive virtual environment.The final VES system (February 2000) contains multimedia material, CBTproducts, and also additional background materials, such as passages from schoolbooks, or Internet resources. A major strength of VES is that a large consortium of educational publishers supports it. Over 20 publishers from fourcountries participate in VES providing content and designing the system in such a way that VES fits into the working process of publishing houses. Therefore,a smooth work-flow for delivery of material is guaranteed, and VES has the potential to become in short time one of the primary providers of on-line material in the major participating countries, that is, Austria, Italy and Greece. In order to integrate schools in the design process, VES has established a continuous feedback process in each of the three VES countries.The VES system architecture is based on a network of distributed multimedia databases, which act as the data servers within the VES. One server per participating country (Austria, Italy, Greece) has been installed. These servers can be accessed via a standard Web browser. For each user group, a special Web-based Graphical User Interface was designed. Publishers are provided witha supporting interface for uploading and monitoring the use of teaching material,teachers have search and compose facilities assisted by intelligent wizards, while pupils access the system through a specifically designed interface to work with selected learning material as well as mDVEs. In general the VES system has two main technical results: 1. The implementation of a distributed multimedia database for storing the multimedia-value added teaching material and additional Computer Based Training (CBT) products. 2. The development of a 3D mDVE providing pupils with a powerful tool for learning and exchanging knowledge.The VES 3D community consists of mDVEs. These environments have a primary goal of providing educational material and communication facilities to students and teachers through a user-friendly 3D interface. The 3D community described in this paper satisfies the above requirements. First of all it offers multi-user interaction through chat communication and avatar representation. In addition, the described environment is an mDVE and it does not have excessive requirements from the user side. More specifically, the educational material and the virtual worlds are stored in a server and the user can reach the 3D community through a Web browser with the use of appropriate plug-ins. After the evaluation of the VES 3D community by the end users, the need is raised for the improvement of the system in order to satisfy their needs in a more efficient way. Our proposal of an LVE application is presented in this paper.

This paper describes our work on educational applications with the use of virtual environments. This work involves the development of the VES 3D community,the evaluation of this community and the new direction and its improvement according to the evaluation. The development of the VES 3D community has given us the opportunity to deal with many interesting technical issues, concerning the creation and usage of multi-user virtual environments. In addition to the technical issues that we have encountered, the educational issues that have come up while using this application have been interesting too, and they help us use the new ways of communication and interaction that distributed virtual reality technologies offer in a more efficient manner. In order to evaluate this environment, we have distributed evaluation sheets to teacher, pupils and schools.To enable us to amend the current environment according to teachers and students evaluation results and to offer to a more suitable educational environment,we have reviewed the VES 3D community and propose additional functionality and a new efficient architecture to support the functional specifications of an LVE application. Some of the functional specifications require no time at all to implement as they are offered as basic services of the server (e.g. text chat system,moderated discussions, authentication-registration service, monitoring of the space availability of the virtual rooms, etc.). Furthermore, with the appropriate configuration the server could support some other specifications as well (defining a maximum number of participating users, restricting multi-user scenes, etc.).Many of the functional specifications require additional implementation time after the virtual worlds are created. The development of the lectures’ virtual worlds where certain events and material should be shared among the various users requires the editing of the VRML files in order to include the event sharing mechanism of the blaxxun server. Other features such as the control interface of the teachers, the uploading mechanism, the configuration and authorization mechanisms of the shared space require the development of the appropriate Java and JavaScript programs that can work in combination with the VRML files.Our next step is to design and implement the required virtual worlds. Certain care is given to the design of the event sharing mechanism in order to avoid possible future problems. The development of this application will give us the opportunity to deal with many interesting technical issues, concerning the creation and usage of virtual environments and shared spaces for educational purposes.