**6. Conclusions and future work**

It is crucial to be able to share user-designed software components to enable richer contents and behaviours in the future development of MUVE systems. In previous work, we have designed a mechanism under OSGi to facilitate dynamic installation of user-designed software components in IMNET. In this work, we have extended the MUVE system to allow the semantics of the objects and avatars in the virtual environment to be described in the form of ontology. This provides a standard way for the software components to acquire semantic information of the world for further reasoning. We have used two types of examples: path planning and social interaction, to show how users can design their own code to facilitate richer or autonomous behaviours for their avatars (possibly virtual). We hope that these examples will shed some lights on the further development of object ontology and more sophisticated applications.

## **7. Acknowledgement**

This research was funded in part by the National Science Council of Taiwan, R.O.C., under contract No. NSC96-2221-E-004-008. The paper is extended from a conference paper published in the International Conference on Virtual Reality Continuum and Its Applications in Industry (VRCAI2008)

### **8. References**

182 Applications of Virtual Reality

In the second scenario, user1 arranged a virtual user called door-keeper to watch the door and provide information to potential guests (Fig. 18(1~2)). When user2 entered a designated region, the doorkeeper would turn to face user2 and ask: "May I help you?" At the first encounter, user2 just entered this area by accident and therefore chose the answer: "Just look around." The doorkeeper replied: "Have a good day!" (Fig. 18(3~5)) The state of the doorkeeper in this interaction was then set to FINISH. After user2 left the area, the state was restored to IDLE (Fig. 18(6)). Assume that after some period of time, user2 approached the doorkeeper again for the second time. This time user2 chose: "I'm looking for my friend." The doorkeeper replied: "Who's your friend?" Then user2 answered: "Jerry." At this moment, the doorkeeper queried the avatar ontology of user1 (named Jerry) to see if user2 is in his friend list. If so, the doorkeeper would inform user2 the current position of user1. Otherwise, the doorkeeper would answer: "Sorry, Jerry does not seem to know you." If there is no such a user called Jerry, the doorkeeper would answer: "Jerry is not in this

Fig. 18. An example of interaction between a real users and a virtual user (doorkeeper)

(7) (8) (9)

(1) (2) (3)

(4) (6)

(5)

It is crucial to be able to share user-designed software components to enable richer contents and behaviours in the future development of MUVE systems. In previous work, we have designed a mechanism under OSGi to facilitate dynamic installation of user-designed

world." (Fig. 18(7~9))

**6. Conclusions and future work** 


**0**

**10**

**An Overview of Interaction Techniques and 3D**

Since the emergence of databases in the 1960s, the volume of stored information has grown exponentially every year (Keim (2002)). This information accumulation in databases has motivated the development of a new research field: Knowledge Discovery in Databases (KDD) (Frawley et al. (1992)) which is commonly defined as the extraction of potentially useful knowledge from data. The KDD process is commonly defined in three stages: pre-processing, Data Mining (DM), and post-processing (Figure 1). At the output of the DM process (post-processing), the decision-maker must evaluate the results and select what is interesting. This task can be improved considerably with visual representations by taking advantage of human capabilities for 3D perception and spatial cognition. Visual representations can allow rapid information recognition and show complex ideas with clarity and efficacy (Card et al. (1999)). In everyday life, we interact with various information media which present us with facts and opinions based on knowledge extracted from data. It is common to communicate such facts and opinions in a virtual form, preferably interactive. For example, when watching weather forecast programs on TV, the icons of a landscape with clouds, rain and sun, allow us to quickly build a picture about the weather forecast. Such a picture is sufficient when we watch the weather forecast, but professional decision-making is a rather different situation. In professional situations, the decision-maker is overwhelmed by the DM algorithm results. Representing these results as static images limits the usefulness of their visualization. This explains why the decision-maker needs to be able to interact with the data representation in order to find relevant knowledge. Visual Data Mining (VDM), presented by Beilken & Spenke (1999) as an interactive visual methodology "to help a user to get a feeling for the data, to detect interesting knowledge, and to gain a deep visual understanding of the data set", can

In 2D space, VDM has been studied extensively and a number of visualization taxonomies have been proposed (Herman et al. (2000), Chi (2000)). More recently, hardware progress has led to the development of real-time interactive 3D data representation and immersive Virtual Reality (VR) techniques. Thus, aesthetically appealing element inclusion, such as 3D graphics and animation, increases the intuitiveness and memorability of visualization. Also, it eases the perception of the human visual system (Spence (1990), Brath et al. (2005)). Although there is still a debate concerning 2D vs 3D data visualization (Shneiderman (2003)), we believe that

**1. Introduction**

facilitate knowledge discovery in data.

**Representations for Data Mining**

Ben Said Zohra1, Guillet Fabrice1, Richard Paul2,

Blanchard Julien<sup>1</sup> and Picarougne Fabien<sup>1</sup>

<sup>1</sup>*University of Nantes* <sup>2</sup>*University of Angers*

*France*

Salomon, B.; Garber, M.; Lin, M. C. & MANOCHA, D. (2003). Interactive Navigation in Complex Environment Using Path Planning. *Proc. of the 2003 Symposium on Interactive 3D graphics*.
