We study ways to reduce cybersickness and improve the user's experience in virtual reality applications that use a HMD and a Gamepad as interaction devices. Our approach consists on a revision of the design space of such tasks in order to identify ways to minimize user's perceived movements. In this paper we concentrate on the task of navigation in realistic scenarios, such as the Tuscany Demo [12]. We performed three user studies in order to identify the most problematic issues in this scenario and the effects of geometry and interaction techniques in the overall experience, in particular in the task of moving up and down stairs. As a result of these studies, we propose the use of invisible ramps on top of stairs, in order to minimize users' perceived movements while moving through stairs and hence reduce users' discomfort.

This paper presents our research on the Interaction Techniques Markup Language (InTml). Our final goal in this work is to find ways to evolve and fit virtual reality (VR) applications over heterogeneous hardware platforms, a process we call retargeting. Toward this goal, we have developed a hardware-independent, componentbased, formal model that describes the execution of VR applications; an XML language for describing complex and implementation-independent VR applications; a methodology for InTml-based development; a manual way to isolate and replace interaction techniques as a contribution to VR retargeting; and a set of tools for development support. This paper describes these topics and states future directions of our research.

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Digitizing specular and transparent objects pose significant problems using traditional 3-D scanning techniques due to the reflection and refraction that interfere with the optical scanning process used for triangulation. In this paper, we present how one can digitize those difficult objects by modifying a commercial 3-D acquisition system with an interchangeable ultraviolet and infrared light source. Experimental results show that the proposed technique can generate accurate 3-D models of these optically challenging objects without major modifications to the 3-D scanner. The results were obtained without preprocessing or multi-view manipulations. The precision of the 3-D measurements is evaluated relative to the visible spectrum acquisition obtained by painting the test objects with matte paint to suppress optical difficulties. Results shows that wavelength changes in the 3-D acquisition system do not change the scanner precision but solve many of the issues that specular and transparent objects poses.

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This paper shows preliminary results on how interactive 3D product presentations affect buyer behavior in e-commerce applications over the Internet. We conducted two experiments involving simulated online shopping trips, in which subjects saw some products with 3D presentations and made product choices. The results show that the availability of interactive 3D product presentations instead of still images may affect some important aspects of buyer behavior, including the amount of time spent examining products and purchase likelihood.

Virtual reality (VR) is a computer-based technology that can be used by professionals of many different fields to simulate an environment with a high feeling of presence and immersion. Nonetheless, one main issue when designing such environments is to provide user interactions that are adapted to the tasks performed by the users. Thus, we propose here a task-centred methodology to design and evaluate these user interactions. Our methodology allows for the determination of user interaction designs based on previous VR studies, and for user evaluations based on a task-related computation of usability. Here, we applied it on the hazard identification case study, since VR can be used in a preventive approach to improve worksite safety. Once this task and its related user interactions were analysed with our methodology, we obtained two possible designs of interaction techniques for the worksite exploration subtask. About their usability evaluation, we proposed in this study to compare our task-centred evaluation approach to a non-task-centred one. Our hypothesis was that our approach could lead to different interpretations of user study results than a non-task-centred one. Our results confirmed our hypothesis by comparing weighted usability scores from our task-centred approach to unweighted ones for our two interaction techniques.

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