**1. Introduction**

170 Virtual Reality and Environments

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Virtual environment (VE) can be defined as a computer generated three dimensional model environment; in which a user feels as if he/she is present in it and the user can interact intuitively with objects contained within it (Wilson, 1999). While being advantageous in experiencing new environment without having to build the real thing, the experience comes with some side effect for some. When interacting with VE through output and input devices, it has been reported that some users experienced negative side effects by being immersed into the graphically rendered virtual worlds. One of side effect is known as cyber sickness i.e. especially affecting the vision (Stanney *et all*, 1998; Barret, 2004). Stanney *et all* (1998) further mentioned that for VEs to be effective and well received by their users; while avoiding unwanted side effect, human being's limitation needs to be considered during the VE design stage. It is highly essential to ensure that advances in VE technology will not be at the expense of human well being.

Ergonomics is a branch of science that is concerned with the achievement of optimal relationship between workers and their work environment (Tayyari, F. and Smith, J.L., 1997). Since human being's limitation is crucial in the design process of a virtual environment, implementation of ergonomics will bring about an optimal VE experience for users. Good design incorporating ergonomics consideration will enhance the communication between the user and the virtual world. Since several ergonomic factors contribute to good VE design, there is a need to investigate what are the critical ergonomics design criteria.

Most ergonomics researches are related to the ergonomic design criteria of human computer interaction. They are focused on physical ergonomics such as visual display terminal (VDT). Stewart, T. (1995) exhibited the importance of ergonomics standards for computer equipment (IS0 9241), and the necessity in understanding how to use them when selecting

Ergonomics Design Criteria of a Virtual Environment 173

presents a virtual robot activity for storage loading and unloading (SLU) process (shown in Figure 1). It was developed using direct X and Dark Basic Professional. The Autodesk 3DS Max software was used to build the virtual object. The VE was displayed through a projector on a wide screen. The projector was connected via cable to a laptop controlled by a keyboard and mouse. This wide screen allows the projection of stereoscopic images where

A qualitative assessment was conducted through the use of questionnaire. The questionnaire was developed to identify the visual symptoms of the virtual environment variables / attributes investigated. The questionnaire consists of two principal parts. The first part contains the question with seven response option. This is aimed to identify the visual problems experienced during or after interacting with the VE. The second part contains questions to identify the level of symptoms experienced based on the answers of the previous part. The answers to the questions in the second part were of the ordinal

Statistical analysis was conducted to analyse the effect/relationship between independent variable and dependent variable. Non parametric statistic was implemented involving descriptive statistic and statistical binomial test. The tests were on hypotheses about the effect of each attributes or variables of the virtual environment on the incidence of visual

each eye will see the slightly shifted images.

Fig. 1. Snap shot of Virtual Robot Manufacturing System

**2.2.2 Questionnaires** 

**2.2.3 Statistical analysis** 

symptoms. The hypotheses developed were:

data type.

or designing visual display unit (VDU) equipment and systems**.** When Menozzi, M., *et al* (1999) conducted studies comparing cathode ray tube (CRT) display and liquid crystal display (LCD) for their suitability in visual tasks in VDU, it was found that LCD provided better viewing conditions compared to CRT display. Nichols, S. (1999) investigated the design of VR equipment in respect to the physical ergonomics such as head mounted display (HMD) and hand-held input devices and the problems associated with it. Shieh and Lin (2000) investigated the effect of screen type, ambient lighting and colour combination on VDT to visual performance and found that those factors do affect VDT performance. Lin (2003) studied the effects of contrast ratio and text colour on visual performance using TFT-LCD and found that contrast ratio significantly affects visual performance. In 2007, after being approved by ANSI on 14th November, the Human Factor Engineering Society published the new national standard for human factor engineering of computer workstation (ANSI/HFES100), which eventually becomes the comprehensive ergonomics guideline in the design of a VDT.

Ergonomics research related to virtual environment has been conducted in the past, but the focus of the research is only on the use of VE as a tool in ergonomics analysis (Shaikh,I., *et al*, 2004; Colombo and Cugini, 2005; Pappas, M., *et al*, 2005; Dukic, T., *et al,* 2007; Hu, B, *et al*, 2011). Shaikh,I., *et al*, (2004) studied on participatory ergonomics using VR and found that VR system will help towards designing better workplaces. Colombo and Cugini (2005) researched on virtual humans and prototypes, evaluating ergonomics and safety. While Pappas, M. *et al* (2005) investigated on ergonomic evaluation of virtual assembly tasks. Other researchers such as Dukic, T *et al* (2007) researched on the evaluation of ergonomics in a virtual manufacturing process and Hu, B. *et al* (2011) presented preliminary experimental results on the relationship between ergonomic measurements in VE and RE for some typical "drilling" tasks.

It has been noted that no research on ergonomics design criteria for designing a virtual environment has been reported. Thus, the objective of this study in identifying the ergonomics design criteria for designing a Virtual Environment is imperative.
