Human centred design of 3-D interaction devices to control virtual environments

Abstract

It is commonly acknowledged that user needs should drive design, but often technical influences prevail. Currently, there are no standard interaction devices or interfaces used in 3-D environments, and there is a lack of specific best practice guidelines to develop these. This paper discusses the process of collecting feedback on prototype designs for VR/VE interaction devices from both expert users and non-expert users, and demonstrates how the information gained from human centred evaluation can be used to further the design process. Experiment 1 examined the usability of two magnetically tracked interaction devices with three different types of menus (Sphere, Linear and Fan). Quantitative and qualitative analysis was carried out on the results, and usability problems with the menus and devices are discussed. The findings from this experiment were translated into general design guidance, in addition to specific recommendations. A new device was designed on the basis of some of these recommendations and its usability was evaluated in Experiment 2. Feedback from participants in Experiment 2 demonstrated that the design recommendations emerging from Experiment 1 were successfully applied to develop a more usable and acceptable device.

Introduction

One of the major problems when designing and developing new interaction techniques for 3-D environments is the lack of specific best practice guidelines. Reported approaches to 3-D environment design (e.g. Kaur, 1998; Gabbard et al., 1999a; Bowman et al., 2001a, Bowman et al., 2001b; Eastgate, 2001; Wilson et al., 2002) are difficult to translate into specific guidance for use by developers. In this paper, we discuss the design of menus and interaction devices used within immersive environments and how the results from evaluating such designs can be used to begin the development of guidelines.

The Hybrid 6-sided Personal Immersion System (HyPI-6) is a 6-walled 3×3×3 m cubic stereo projection space in which computer-generated images can be projected externally onto the walls. The term ‘hybrid’ refers to the fact that the system can be driven in active (in conjunction with an SGI Onyx) as well as passive (in conjunction with a PC cluster) stereo projection mode. A user standing within the cube feels integrated within a computer-simulated world. Such a projection environment is achieved by a combination of stereoscopic real-time representation, suitable interaction tools with which participants can steer the three-dimensional space around themselves, and special software. Systems which generate virtual worlds have been in use for several years although the number of systems actually installed and in working use is relatively small.

In an average office working environment most employees will be using a standard keyboard and mouse to interact with certain conventional computer hardware and software. However, there is no typical or average VR technology set-up and it is possible that for each facility using a projection display via CAVE technology, a different set of interaction devices are used (a CAVE is a spatially immersive display in the form of a cubic projection room consisting of 3–6 projection screens). Over the past decade, a number of innovative interaction devices have been proposed, but they are still far from becoming standard tools (Zhai, 1998) and selection may have more to do with cost and availability than usability and comfort.

In addition to hardware considerations, there are no standard interface metaphors used in 3-D environments. All too commonly, designers create a menu structure/device which they personally find usable, or worse, attractive, with little concern for the actual usability of these interfaces/devices and the demands which they will place on the non-specialist user. Problems discovered later in real use could easily have been avoided if usability had been a more realistic concern earlier on in the design process. As was seen in early PC technologies, the emphasis in VR/VE design is still much more on overcoming technical limitations and showcasing new capabilities, rather than on user led design. In addition, new interfaces are often designed for new models or applications, resulting in a lack of consistency and restricting the ability of the user to develop common understanding of interaction and navigation methods. As the potential for active use of visualization technologies in industrial applications increases, the need to develop interaction devices and interfaces which are intuitive and easy to use grows.

New, improved interaction devices can be designed through an understanding of usability problems associated with existing devices. The experiments presented in this paper were carried out within the European IST project, VIEW of the Future, and had the aim of guiding the development of new interaction devices. A set of prototype devices with different grip requirements was designed in order to investigate preferences. Non-specialist users cannot be expected to understand some of the technical constraints limiting the design of the prototypes, so we combined input from experts and non-expert users. Experiment 1 was conducted to evaluate the use of two devices with different interfaces. Design recommendations were made on the basis of this study and a new device was developed and evaluated in Experiment 2.