Integrating behavioural design into the virtual environment development process

A number of specifications formalisms have been developed (or applied) to support the abstract design of the behavioural component of the virtual environment interface. These formalisms subscribe to the philosophy that virtual environments should be viewed as hybrid systems which combine discrete and continuous behaviour. A significant deficiency in designing behaviour in this way is that the designs cannot be directly executed and explored in the same manner as an implementation. This limitation makes it difficult for a designer to evaluate the suitability of designs. The thesis presents the Marigold toolset which supports two approaches to evaluating behaviour described using the Flownet hybrid formalism. The first approach involves refining the design to an implementation prototype where it can be explored with users. An emphasis within this approach is a usable means of integrating the behaviour with the components that form the direct interface to the users (the presentation) such as devices. This is achieved by the use of visual data flow networks. The second approach involves the analysis of Flownets so that characteristics of the design can be automatically checked. A consideration within this approach is a usable means of specifying the properties and understanding the results of the analysis. A secondary focus of the thesis is a requirements specification approach for virtual environments. This is motivated by reports that one of the problems with the virtual environment development process is an accurate interpretation of the users requirements by the designers. The approach elicits requirements in a language familiar to the users, and translates these into a specification that can be used by a designer to construct designs. The Primrose tool has been developed to support this approach.