Virtual environments (VEs) are a relatively new type of human-computer interface in which users perceive and act in a three-dimensional world. The designers of such systems cannot rely solely on design guidelines for traditional two-dimensional interfaces, so usability evaluation is crucial for VEs. This paper presents an overview of VE usability evaluation, to organize and critically analyze diverse work from this field. First, we discuss some of the issues that differentiate VE usability evaluation from evaluation of traditional user interfaces such as GUIs. We also present a review of some VE evaluation methods currently in use, and discuss a simple classification space for VE usability evaluation methods. This classification space provides a structured means for comparing evaluation methods according to three key characteristics: involvement of representative users, context of evaluation, and types of results produced. Finally, to illustrate these concepts, we compare two existing evaluation approaches: testbed evaluation [Bowman, Johnson, & Hodges, 1999], and sequential evaluation [Gabbard, Hix, & Swan, 1999]. 1 Introduction and

A useful function of augmented reality (AR) systems is their ability to visualize occluded infrastructure directly in a user’s view of the environment. This is especially important for our application context, which utilizes mobile AR for navigation and other operations in an urban environment. A key problem in the AR field is how to best depict occluded objects in such a way that the viewer can correctly infer the depth relationships between different physical and virtual objects. Showing a single occluded object with no depth context presents an ambiguous picture to the user. But showing all occluded objects in the environments leads to the “Superman’s X-ray vision ” problem, in which the user sees too much information to make sense of the depth relationships of objects. Our efforts differ qualitatively from previous work in AR occlusion, because our application domain involves farfield occluded objects, which are tens of meters distant from the user. Previous work has focused on near-field occluded objects, which are within or just beyond arm’s reach, and which use different perceptual cues. We designed and evaluated a number of sets of display attributes. We then conducted a user study to determine which representations best express occlusion relationships among far-field objects. We identify a drawing style and opacity settings that enable the user to accurately interpret three layers of occluded objects, even in the absence of perspective constraints. 1

We summarize three evaluations of an educational augmented reality application for geometry education, which have been conducted in 2000, 2003 and 2005 respectively. Repeated formative evaluations with more than 100 students guided the redesign of the application and its user interface throughout the years. We present and discuss the results regarding usability and simulator sickness providing guidelines on how to design augmented reality applications utilizing head-mounted displays.

Rather than relying on costly physical mock-ups of functional assessment and rehabilitation environments, VR offers the option to produce and distribute identical “standard ” environments. Within such digital assessment and rehabilitation scenarios, normative data can be accumulated for performance comparisons needed for assessment, diagnosis and for training purposes. As well, in this manner, reusable archetypic virtual environments constructed for one purpose, could also be applied for clinical applications addressing other purposes. This has now been done with the Virtual Classroom scenario. While originally developed as a controlled stimulus environment in which attention processes could be systematically assessed in children while in the presence of varying levels of distraction, the system is now finding use for other clinical targets. Such applications that are being developed and tested using the Virtual Classroom for other purposes include: 1. Expansion of the range of attention assessment tests (i.e., a “Stroop ” Interference testing system for all ages). 2. A wide field of view system to study eye tracking under distracting conditions with ADHD children using an Elumens VisionStation®. 3. Development of the Virtual Classroom as a tool for anxiety assessment and graduated exposure therapy for children with Social Anxiety

This thesis describes the result of a study performed in partial fulfilment of the requirements

maximum 200 words) The goal of much work in Virtual Environments (VEs) to date has been to produce innovative technology but until recently, there has been very little user-centered, usability-focused research in VEs that will turn interesting applications into usable ones. There is beginning to be at least some awareness of the need for usability engineering within the VE community. A handful of articles address usability concerns for particular parts of the VE usability space. From this point Gabbard and Hix [1997] has proposed a taxonomy about usability characteristics in VEs to help VE usability engineers and designers.

Abstract — Three-dimensional user interfaces (3D UIs) support user tasks in many non-traditional interactive systems such as virtual environments and augmented reality. Although 3D UI researchers have been successful in identifying basic user tasks and interaction metaphors, evaluating the usability of 3D interaction techniques, and improving the usability of many applications, 3D UI research now stands at a crossroads. Very few fundamentally new techniques and metaphors for 3D interaction have been discovered in recent years, yet the usability of 3D UIs in many real-world applications is still not at a desirable level. What directions should 3D UI researchers next explore to improve this situation? In this paper, we make some observations about the history of 3D UIs and the current state-of-the-art. Using this evidence, in addition to our own experience, we argue that 3D UI researchers should approach this problem using some new research approaches, which cluster around the concepts of specificity, flavors, implementation, and emerging technologies. We illustrate and discuss some of these new directions using case studies of research projects undertaken in our group. These explorations indicate the promise of these directions for further increasing our understanding of 3D interaction and 3D UI design, and for ensuring the usability of 3D UIs in future applications. Index Terms—3D user interfaces, 3D interaction, user interface design, usability I.

Since ancient times mathematicians and geometricians use visualisations to describe, discuss, to study and to teach mathematics. In mathematics education visualisations are still used whenever possible to support teaching, to inspire students and feed their need to actually see abstract mathematical facts. In our times virtual reality presents a fascinating, extremely motivating new tool in teachers ’ hands which allows students to see mathematics in three dimensions. This chapter gives an overview of various, mainly immersive, virtual environments that have been developed in the previous 10 years to support mathematics and geometry education. The focus lies on one advanced application for geometry education that has been used and evaluated with over 500 students throughout the years. Findings and teaching experiences are described and discussed. 1

There is a need to develop new usability testing environments and methodologies for unconventional interactive systems. Pursuant to that need, we developed a low-cost test environment for a Head-Mounted Display (HMD)-based, virtual reality system called Osmose. Osmose was difficult to test for many reasons, one of which was its style of interaction. We began setting up the testing environment about two weeks before the start of the usability testing. We learned many lessons throughout the experience. This paper summarizes the study findings, both methodological – how to setup and conduct a usability lab for such an environment – as well as conceptual –the human experiences and behavioral patterns involved in using an immersive environment. Keywords Immersive systems, head-mounted display, usability testing, sensing-based interaction, breathing interaction, virtual reality Copyright © 2007-2008, Usability Professionals ’ Association and the authors. 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.

Virtual environment (VE) design for cognitive rehabilitation necessitates a new methodology to ensure the validity of the resulting rehabilitation assessment. We propose that benchmarking the VE system technology utilizing a user-centered approach should precede the VE construction. Further, user performance baselines should be measured throughout testing as a control for adaptive effects that may confound the metrics chosen to evaluate the rehabilitation treatment. To support these claims we present data obtained from two modules of a user-centered head-mounted display (HMD) assessment battery, specifically resolution visual acuity and stereoacuity. Resolution visual acuity and stereoacuity assessments provide information about the image quality achieved by an HMD based upon its unique system parameters. When applying a user-centered approach, we were able to quantify limitations in the VE system components (e.g., low microdisplay resolution) and separately point to user characteristics (e.g., changes in dark focus) that may introduce error in the evaluation of VE based rehabilitation protocols. Based on