Intuitively Specifying Object Dynamics in Virtual Environments using VR-WISE Bram Pellens Vrije Universiteit Brussel Pleinlaan 2 1050 Brussels +32 2 629 5713 bram.pellens@vub.ac.be Frederic Kleinermann Vrije Universiteit Brussel Pleinlaan 2 1050 Brussels +32 2 629 5713 frederic.kleinermann@vub.ac.be Olga De Troyer Vrije Universiteit Brussel Pleinlaan 2 1050 Brussels +32 2 629 3504 olga.detroyer@vub.ac.be ABSTRACT Designing and building Virtual Environments is not an easy task, especially when it comes to specifying object behavior where either knowledge about animation techniques or programming skills are required. With our approach, VR-WISE, we try to facilitate the design of VEs and make this more accessible to novice users. In this paper, we present how behavior is specified in VR-WISE, as well as the prototype developed for the approach. Categories and Subject Descriptors H.5.1 [Information Interfaces and Presentation]: Multimedia Information Systems – Artificial, augmented, and virtual realities, Evaluation/methodology. General Terms Design. Keywords Virtual Reality, Conceptual Modeling, Design Phase, Behavior 1. INTRODUCTION These days, Virtual Environments (VEs) are used for numerous purposes. Despite the fact that its use has grown, the design and development of VEs is only performed by experienced people since the technology is not very accessible to novice users. This situation is especially noticeable in the development of the behavior. In the complete design process of a VE, specifying the animations of the objects is usually the most difficult bit for inexperienced people [5]. We have developed an approach, called VR-WISE, to support the design phase in the development process of a VE and to enable the specification of a VE at a high-level, free from any implementation aspects. The aim of VR-WISE is to make the design more intuitive, requiring less background and thus making the technology available to a broader public. In this paper, we show how behavior can be specified at a high level and by means of a graphical language. The language is action-oriented; meaning that it focuses on the different actions that an object must be able to perform rather than on the states an object can be in. Specifying behavior in such a way is much more intuitive for non- professionals because the behaviors are specified in a way similar as they would have in natural language. In most animation models for VEs, the lifetime of the objects and their visual representation are not explicitly specified. Usually, it is assumed that the object already exists when the behavior starts; also often the visual representation of the object remains the same throughout the complete behavior. If one wants to go beyond this and deal with such behavior, one needs to resort to programming in order to do so. The graphical specification language proposed here includes modeling constructs to specify changes in the content of the VE over time (e.g., creating, modifying or deleting objects). These modeling constructs complements the ones for specifying the change of the poses of the objects in a VE as available in most modeling tools. The work presented here closely relates to [6] where the design of behavior is also addressed using a graphical notation. Unfortunately, for simple behaviors, the specification becomes large and difficult to read and is therefore not very suitable for novices. In [1] an icon-based approach is presented to specify behaviors of objects in VRML. However, considerable knowledge about the VRML language is required. Similar modeling concepts as ours are introduced in [3]. However, these are limited in such a way that no actual code can be generated for them. A commercial development environment that closely relates to our research is Virtools Dev [7]. Also Virtools allows constructing object behavior graphically by combining a number of primitive building blocks together. However, the function-based mechanism tends to be less comprehensible for novices. 2. VR-WISE AND TOOL SUPPORT The development process in the VR-WISE approach is divided into three (mainly) sequential steps. The Specification step allows the designer to specify the VE at a high level using domain knowledge together with high-level modeling concepts. In this step, the domain objects needed in the VE, the relationships between them as well as their behaviors, the interactions with other objects and with the user are specified. There is a strong similarity between how one describes a VE in our approach and how it would be done using natural language. The Mapping step Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. VRST'06, November 1–3, 2006, Limassol, Cyprus. Copyright 2006 ACM 1-59593-321-2/06/0011...$5.00.