In a co-located collaborative virtual environment, multiple users share the same physical tracked space and the same virtual workspace. When the virtual workspace is larger than the real workspace, navigation interaction techniques must be deployed to let the users explore the entire virtual environment. When a user navigates in the virtual space while remaining static in the real space, his/her position in the physical workspace and in the virtual workspace are no longer the same. Thus, in the context where each user is immersed in the virtual environment with a Head-Mounted-Display, a user can still perceive where his/her collaborators are in the virtual environment but not where they are in real world. In this paper, we propose and compare three methods to warn users about the position of collaborators in the shared physical workspace to ensure a proper cohabitation and safety of the collaborators. The first one is based on a virtual grid shaped as a cylinder, the second one is based on a ghost representation of the user and the last one displays the physical safe-navigation space on the floor of the virtual environment. We conducted a user-study with two users wearing a Head-Mounted-Display in the context of a collaborative FirstPerson-Shooter game. Our three methods were compared with a condition where the physical tracked space was separated into two zones, one per user, to evaluate the impact of each condition on safety, displacement freedom and global satisfaction of users. Results suggest that the ghost avatar and the cylinder grid can be good alternatives to the separation of the tracked space. CCS CONCEPTS• Human-centered computing → Virtual reality; Collaborative interaction; User studies; KEYWORDSVirtual Reality, Collaborative Virtual Environment Permission to make digital or hard copies of part or all 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. Copyrights for third-party components of this work must be honored. For all other uses, contact the owner/author(s). VRST '17, November 8-10, 2017, Gothenburg, Sweden [Fleury et al. 2010] that results from the virtual navigation of both users in the VE. When these two users wear a HMD, they can still perceive each other in the VE but no longer in the real workspace. In that case, we must avoid any possible physical collision between the two users.

This paper presents #FIVE (Framework for Interactive Virtual Environments), a framework for the development of interactive and collaborative virtual environments. #FIVE has been developed to answer the need for an easier and a faster conception and development of virtual reality applications. It has been designed with a constant focus on re-usability with as few hypothesis as possible on the final application in which it could be used. Whatever the chosen implementation for the Virtual Environment (VE), #FIVE : (1) provides a toolkit that eases the declaration of possible actions and behaviours of objects in the VE, (2) provides a toolkit that facilitates the setting and the management of collaborative interactions in a VE, (3) is compliant with distribution of the VE on different setups and (4) proposes guidelines to efficiently create a collaborative and interactive VE. It is composed of several modules, among them, two core modules : the relation engine and the collaborative interaction engine. On the one hand, the relation engine manages the relations between the objects of the environment. On the other hand, the collaborative interaction engine manages how users can collaboratively control objects. The modules that compose the #FIVE framework can be used either independently or simultaneously, depending on the requirements of the application. They can also communicate and work with other modules thanks to an API. For instance, a scenario engine can be plugged to any or both of the #FIVE modules if the application is scenario-based. #FIVE is a work in progress, new core modules will later be proposed. Nevertheless, it has already been used in some VR applications by several persons in our lab. The feedbacks we obtained are rather positive and we intent to further develop #FIVE with additional functionalities, notably by extending it to the control of avatars whether they are controlled by a user or by the system.

Traumatic brain injury (TBI) is a leading cause of long-term disability and death worldwide. This article describes an ongoing research project to design, develop, and evaluate interactive learning simulations that integrate educational materials for uninjured teenagers who have a parent with a TBI. By immersing players in an interactive environment that resembles the gaming world with which most teenagers are familiar, these simulations are designed to help players develop knowledge and skills in circumstances approximating real-life settings. We describe the steps we took, both to consult with families affected by TBI to understand the difficulties teenagers commonly face when they live with a brain-injured parent, and to weave some of these difficulties into a pedagogical drama that can be played as an interactive game.