• Conceptual Modeling has been used with success in different domains such as Information Systems, Web Information Systems, User Interface Modeling, and Software Engineering.
• It has less been used in domains like 3D Modeling and Virtual Reality (VR). VR is a technology to simulate environments and create the effect of an interactive three-dimensional world in which objects have a sense of spatial and physical presence and can be manipulated by the user as such.
• VR has gained a lot of popularity during the last decennia due to e.g., games and applications such as Second Life (Second Life 2007).
• Although a lot of tools are available for developing VR applications, it is time-consuming, expensive, complex and specialized.
• One of the reasons is that the development of VR applications directly starts at the implementation level.
• The virtual world that needs to be created must be expressed in terms of low level VR building blocks, such as textures, shapes, sensors, interpolators, etc.
• This requires a considerable amount of background knowledge in VR.
• In addition, it makes the gap between the application domain and the level at which the virtual world needs to be specified very large, and this makes the translation from the concepts in the application domain into implementation concepts a very difficult issue.
• Like for other domains, introducing a Conceptual Design phase in the development process of a VR application may help the VR community in several ways.
• As Conceptual Modeling will introduce a mechanism to abstract from implementation details, it will reduce the complexity of developing a VR application.
• In addition, if well done, such an abstraction layer can also hide the specific jargon used in VR and then no special VR knowledge will be needed for making the conceptual design.
• Therefore, also non-technical people (like the customer or the end-user) can be involved in the development and this will improve the communication between the developers and the other stakeholders.
• In addition, by involving the customer more closely in the design process of the VR application, earlier detection of design flaws is possible.
• All this could help in realising more VR applications in a shorter time.
• However, Conceptual Modeling for VR poses a lot of challenges as in VR applications a number of aspects, not present in classical software or information systems, are very essential.
• For example, VR applications are 3D worlds composed of 2D and 3D objects and often deal with 3D complex objects, for which the way the parts are connected will influence the way the complex objects can behave.
• Furthermore, to realize dynamic and realistic worlds, objects may need complex (physical) behaviors. Therefore, new modeling concepts, not present in classical conceptual modeling languages such as ER, ORM and UML, are needed

Virtual Reality Modeling Language

• VRML (Virtual Reality Modeling Language) is a language for describing three-dimensional ( 3-D ) image sequences and possible user interactions to go with them. Using VRML, you can build a sequence of visual images into Web settings with which a user can interact by viewing, moving, rotating, and otherwise interacting with an apparently 3-D scene.
• For example, you can view a room and use controls to move the room as you would experience it if you were walking through it in real space.
• To view a VRML file, you need a VRML viewer or browser, which can be a plug-in for a Web browser you already have.
• Among viewers you can download for the Windows platforms are blaxxun's CC Pro, Platinum's Cosmo Player, WebFX, WorldView, and Fountain. Whurlwind and Voyager are two viewers for the Mac.

Physical Modelling

• A class of virtual environments is concerned with the representation of behaviour that is apparent in the real world. In order to model this behaviour, sophisticated physical models are required.
• The development of these models, classed asphysically-based modelling, is based upon the fundamental concepts of Newtonian dynamics.
• Considerable research into physically-based modelling has already been conducted by the computer graphics community, permitting realistic animation of object motion.
• The application of physical models to virtual environments poses further problems, not least that of real-time execution in a fully interactive environment.