Social experience can deeply impact on gaming experience and is often used to increase enjoyment and retention. In the literature two main categories of social interaction can be identified: competition and collaboration. Player engagement has been widely studied under different conditions related to the type of social interaction taking place during the game. However, rich and newly available contexts based on emerging paradigms, such as those enabled by Natural User Interfaces, have not been yet extensively addressed. In the current study the impact of collaborative and competitive goal structures on player engagement, awareness and social presence is evaluated in the context of a jigsaw puzzle game taking place in a Shared Virtual Environment using a highly immersive setup exploiting natural user interaction.

Augmented Reality (AR) is a technology that allows users to view and interact in real time with virtual images seamlessly superimposed over the real world. AR systems can be used to create unique collaborative experiences. For example, co-located users can see shared 3D virtual objects that they interact with, or a user can annotate the live video view of a remote worker, enabling them to collaborate at a distance. The overall goal is to augment the face-to-face collaborative experience, or to enable remote people to feel that they are virtually co-located. In this special issue on collaboration in augmented reality, we begin with the visions of science fiction authors of future technologies that might significantly improve collaboration, then introduce research articles which describe progress towards these visions, finally we outline a research agenda discussing the work still to be done.

In this half-day workshop we will explore how Augmented Reality (AR) and Mediated Reality (MR) can be used to develop radically new types of collaborative experiences that overcome some of the limitations of current conferencing systems. In combination, AR and MR technologies could be used to merge the shared perceived realities of different users as well as enriching their own individual experience in a collaborative task. The goal of the workshop is to bring together researchers who are interested developing collaborative systems using AR and MR technologies. They will build a picture of current and prior research on collaboration in AR and MR as well as set up a common research agenda for work going forward. Topics of the workshop will address open research issues and include but are not restricted to the following: •Case studies on using MR/AR for collaboration •Tools for building collaborative MR/AR systems •Effects of MR/AR on trust, presence, and coordination •Interaction models for collaboration in MR/AR •Tools for collaboration in MR/AR •Collaboration awareness in MR/AR.

This poster introduces a fully immersive Mixed Reality system we have recently developed, where the user is free to walk inside a virtual scenario while wearing a HMD. The novelty of the system lies in the fact that users can see and use their real hands — by means of a Kinect-like camera mounted on the HMD — in order to naturally interact with the virtual objects. Our working hypothesis are that the introduction of the photorealistic capture of users' hands in a coherently rendered virtual scenario induces in them a strong feeling of presence and embodiment without the need of using a synthetic 3D modelled avatar as a representation of the self. We also argue that the users' ability of grasping and manipulating virtual objects using their own hands not only provides an intuitive interaction experience, but also improves self-perception as well as the perception of the environment.

This paper presents a novel fully immersive Mixed Reality system that we have recently developed where the user freely walks in a life-size virtual scenario wearing an HMD and can see and use her/his own body when interacting with objects. This form of natural interaction is made possible in our system because the user's hands are real-time captured by means of a RGBD camera on the HMD. This allow the system to have in real-time a texturized geometric mesh of the hands and body (as seen from her/his own perspective) that can be rendered like any other polygonal model in the scene. Our hypothesis is that by presenting to the users an egocentric view of the virtual environment "populated" by their own bodies, a very strong feeling of presence is developed as well.

Mobile-based collaboration tools are increasingly used for communication and information sharing in delivering healthcare services that need collaboration across different geographical locations. Some of the typical features found in the collaboration tools include video conferencing facility, image

Telehealth services research projects often require to access a variety of data sources under different data access policies and privacy constrains. There is a need to link these clinical and administrative records from different data custodians and produce a research data for analytics. One of the

Industrial uses of Augmented Reality (AR) are growing, however their uses are consistently fashioned with an emphasis on consumption, delivering additional information to the worker to assist them in the completion of their job. A promising alternative is to allow user data creation during the actual process by the worker performing their duties. This not only allows spatially located annotations to be produced, it also allows an AR scene to be developed in-situ and in real-time. Tangible markers offer a physical interface while also creating physical containers to allow for fluent interactions. This form factor allows both attached and detached annotations, whilst allowing the creation of an AR scene during the process. This annotated scene will allow asynchronous collaboration to be conducted between multiple stakeholders, both locally and remotely. In this paper we discuss our reasoning behind such an approach, and present the current work on our prototype created to test and validate our proposition.

Recent advance in the design of near-eye displays means that the technology is mature for industrial use. A near eye display has been used as part of a remote mobile guiding system for maintenance operators in mines. In this system, a near eye display is mounted on a helmet worn by a mobile operator to display visual aids sent from a remote helper. The near eye display is partially occluding the view of the operator. In this paper we are interested in exploring the extent to which the partial occlusion of the operator's view is affecting his spatial understanding. In particular, we present an exploratory study investigating the potential impact of the near-eye display on spatial awareness of the operator. Usability was also studied. The study found no evidence showing that near-eye displays had negative impact on spatial awareness and users were also positive about the usability of the near-eye display for remote maintenance.