LLM-based embodied agents are recently emerging in VR, supporting various scenarios such as pedagogical assistants, virtual companions, and NPCs for games. These agents hold potential to enhance user interactions but require thoughtful design to cater diverse user needs and contexts. We present an architecture that leverages different LLM modules to enable conversational interactions with an embodied agent in multi-user VR. Our system’s primary goal is to facilitate immersive tailoring through conversational input, allowing users to dynamically adjust an agent’s behavior and properties (e.g., role, personality, and appearance), directly within the virtual space, rather than during development or via separate interfaces. We evaluate the system’s performance, measuring latency during tailoring tasks, and share insights from a six-week study involving five users exploring various scenarios. While the approach shows promise, challenges remain, including reducing latency in the speech-to-text-to-speech pipeline and addressing the black-box limitations of LLMs, highlighting areas for future research.

This paper presents an openly available implementation of a modular pipeline architecture for character animation. It effectively decomposes frequently necessary processing steps into dedicated character processors, such as copying data from various motion sources, applying inverse kinematics, or scaling the character. Processors can easily be parameterized, extended (e.g., with AI), and freely arranged or even duplicated in any order necessary, greatly reducing side effects and fostering fine-tuning, maintenance, and reusability of the complex interplay of real-time animation steps.

This paper presents a novel experiment investigating the relationship between virtual disembodiment and time perception in Virtual Reality (VR). Recent work demonstrated that the absence of a virtual body in a VR application changes the perception of time. However, the effects of simulating an out-of-body experience (OBE) in VR on time perception are still unclear. We designed an experiment with two types of virtual disembodiment techniques based on viewpoint gradual transition: a virtual body’s behind view and facing view transitions. We investigated their effects on forty-four participants in an interactive scenario where a lamp was repeatedly activated and time intervals were estimated. Our results show that, while both techniques elicited a significant virtual disembodiment perception, time duration estimations in the minute range were only shorter in the facing view compared to the eye view condition. We believe that reducing agency in the facing view is a key factor in the time perception alteration. This provides first steps towards a novel approach to manipulating time perception in VR, with potential applications for mental health treatments such as schizophrenia or depression and for improving our understanding of the relation between body, virtual body, and time.

The utilization of virtual reality (VR) technology has shown promise in various therapeutic applications, particularly in exposure therapy for reducing fear of certain situations objects or activities, e.g. fear of height, or negative evaluation of others in social situations. VR has been shown to yield positive outcomes in follow-up studies, and provides a safe and ecological therapeutic environment for therapists and their patients. This paper presents a collaborative effort to develop a VR speech therapy system which simulates a virtual audience for users to practice their public speaking skills. We describe a novel web-based graphical user interface that enables therapists to manage the therapy session using a simple timeline. Lastly, we present the results from a qualitative study with therapists and teachers with functional dysphonia, which highlight the potential of such an application to support and augment the therapists' work and the remaining challenges regarding the design of natural interactions, agent behaviours and scenario customisation for patients.

This paper presents the development and preliminary evaluation of a personality enhancer behaviour model for virtual audiences to increase their realism and individualism. We conducted a systematic literature review and identified sixteen posture parameters to modify seated animations dynamically, calling them personality enhancers. We grouped them into four main categories: body, gaze, face and gesture behaviour modifiers. We implemented a unique animation modifier system on top of a game engine to apply these personality enhancers on existing pre-recorded generic seated animations. The first results with sixty participants in an online video survey show that the model can successfully simulate individuals with low and high levels of extroversion as well as with low and high levels of emotional stability.

This paper investigates the relationship between perceived object motion and the experience of time in virtual environments. We developed an application to measure how the motion properties of virtual objects and the degree of immersion and embodiment may affect the time experience. A first study (n = 145) was conducted remotely using an online video survey, while a second study (n = 60) was conducted under laboratory conditions in virtual reality (VR). Participants in both studies experienced seven different virtual objects in a randomized order and then answered questions about time experience. The VR study added an "embodiment" condition in which participants were either represented by a virtual full body or lacked any form of virtual body representation. In both studies, time was judged to pass faster when viewing oscillating motion in immersive and non-immersive settings and independently of the presence or absence of a virtual body. This trend was strongest when virtual pendulums were displayed. Both studies also found a significant inverse correlation between the passage of time and boredom. Our results support the development of applications that manipulate the perception of time in virtual environments for therapeutic use, for instance, for disorders such as depression, autism, and schizophrenia. Disturbances in the perception of time are known to be associated with these disorders.

This article explores the effect of one's body representation on time perception. Time Perception is modulated by a variety of factors including, e.g., the current situation or activity, it can display significant disturbances caused by psychological disorders, and it is influenced by emotional and interoceptive states, i.e., "the sense of the physiological condition of the body". We investigated this relation between one's own body and the perception of time in a novel Virtual Reality (VR) experiment explicitly fostering user activity. Forty-Eight participants randomly experienced different degrees of embodiment: i) without an avatar (low), ii) with hands (medium), and iii) with a high-quality avatar (high). Participants had to repeatedly activate a virtual lamp and estimate the duration of time intervals as well as judge the passage of time. Our results show a significant effect of embodiment on time perception: time passes slower in the low embodiment condition compared to the medium and high conditions. In contrast to prior work, the study provides missing evidence that this effect is independent of the level of activity of participants: In our task, users were prompted to repeatedly perform body actions, thereby ruling-out a potential influence of the level of activity. Importantly, duration judgements in both the millisecond and minute ranges seemed unaffected by variations in embodiment. Taken together, these results lead to a better understanding of the relationship between the body and time.

This paper presents the first prototype of a virtual audience system (VAS) specifically designed as a training tool for conference talks. This system has been tailored for university seminars dedicated to the preparation and delivery of scientific talks. We describe the required features which have been identified during the development process. We also summarize the preliminary feedback received from lecturers and students during the first deployment of the system in seminars for bachelor and doctoral students. Finally, we discuss future work and research directions. We believe our system architecture and features are providing interesting insights on the development and integration of VR-based educational tools into university curriculum.

Multimodal Interfaces (MMIs) have been considered to provide promising interaction paradigms for Virtual Reality (VR) for some time. However, they are still far less common than unimodal interfaces (UMIs). This paper presents a summative user study comparing an MMI to a typical UMI for a design task in VR. We developed an application targeting creative 3D object manipulations, i.e., creating 3D objects and modifying typical object properties such as color or size. The associated open user task is based on the Torrence Tests of Creative Thinking. We compared a synergistic multimodal interface using speech-accompanied pointing/grabbing gestures with a more typical unimodal interface using a hierarchical radial menu to trigger actions on selected objects. Independent judges rated the creativity of the resulting products using the Consensual Assessment Technique. Additionally, we measured the creativity-promoting factors flow, usability, and presence. Our results show that the MMI performs on par with the UMI in all measurements despite its limited flexibility and reliability. These promising results demonstrate the technological maturity of MMIs and their potential to extend traditional interaction techniques in VR efficiently.

The perception of time is closely related to our well-being. Psycho-pathological conditions such as depression, schizophrenia and autism are often linked to a disturbed sense of time. In this paper we present a novel framework called Metachron, which is intended to support research in the field of time perception and manipulation in Virtual Reality (VR). Our system allows the systematic modification of events in real time along the three main event axes i) Velocity, ii) Syncronicity and iii) Density. Our future work will investigate the influence of each dimension on the passage of time (varying velocity of time flow) and the structure of time (varying synchronicity of events), which should provide insights for the design of VR diagnostic and therapeutic tools.

This paper introduces a method for computing the difficulty of selection tasks in virtual environments using pointing metaphors by operationalizing an established human motor behavior model. In contrast to previous work, the difficulty is calculated automatically at run-time for arbitrary environments. We present and provide the implementation of our method within Unity 3D. The difficulty is computed based on a contextual analysis of spatial boundary conditions, i.e., target object size and shape, distance to the user, and occlusion. We believe our method will enable developers to build adaptive systems that automatically equip the user with the most appropriate selection technique according to the context. Further, it provides a standard metric to better evaluate and compare different selection techniques.

Virtual Reality (VR) has always been considered a promising medium to support designers with alternative work environments. Still, graphical user interfaces are prone to induce attention shifts between the user interface and the manipulated target objects which hampers the creative process. This work proposes a speech-and-gesture-based interaction paradigm for creative tasks in VR. We developed a multimodal toolbox (MTB) for VR-based design applications and compared it to a typical unimodal menu-based toolbox (UTB). The comparison uses a design-oriented use-case and measures flow, usability, and presence as relevant characteristics for a VR-based design process. The multimodal approach (1) led to a lower perceived task duration and a higher reported feeling of flow. It (2) provided a higher intuitive use and a lower mental workload while not being slower than an UTB. Finally, it (3) generated a higher feeling of presence. Overall, our results confirm significant advantages of the proposed multimodal interaction paradigm and the developed MTB for important characteristics of design processes in VR.

This paper presents an experiment evaluating the effects of virtual agents' language proficiency on whether they are perceived as a native speakers or not. Our first results indicate that beyond 10% word order mistakes and 25% infinitive mistakes, virtual agents are perceived as non-native speakers, even though their appearance and non-verbal behaviour were not altered. We believe these thresholds constitute interesting guidelines possibly simplifying the design of non-native speaker simulations.

In this paper, we investigated the impact of an egocentric simulated frame of reference, the so-called simulated CAVE, on three type of travel techniques: Steering, Jumping and Sliding. Contrary to suggestions from previous work, no significant differences were found regarding spatial awareness between all techniques with or without the simulated CAVE. Our first results also showed a negative effect of the simulated CAVE on participants' motion sickness for every technique, while confirming that the Jumping is eliciting less motion sickness with or without it.

In this paper, we describe the implementation and performance of a Virtual Audience perception model for Virtual Reality (VR). The model is a VR adaptation of an existing desktop model. The system allows a user in VR to easily build and experience a wide variety of atmospheres with small or large groups of virtual agents.The paper describes results of early evaluations for this model in VR. Our first scalability benchmark results demonstrated the ability to simultaneously handle one hundred virtual agents without significantly affecting there commended frame rate for VR applications.This research is conducted in the context of a classroom simulation software for teachers’ training.

This paper presents a novel technique of navigation in Virtual Reality (VR) called Drone-Steering. This technique has been designed to facilitate path learning and traveling in VR by reducing both cybersickness and disorientation. We compared this technique to traditional Hand-Steering in a landmark-free environment. Our first experiment confirmed a significantly lower level of cybersickness during traveling and significantly better path learning. We believe that our technique constitutes a promising alternative to current VR navigation techniques, and will especially interest researchers and developers targeting large VR environments.

This article investigates the impact of waiting in Virtual Reality (VR) on the perception of time. We manipulated the visual quality of a virtual room replicating a real one (360-picture vs. 3D-model) with and without avatar embodiment (no-avatar vs. avatar). We only observed a significant difference in the estimated time duration between the real and the virtual worlds when using no avatar within a 3D model of the room. Our early results suggest that a VR environment with an avatar and a simple 3D model or 360 picture room is not significantly perturbing time perception and thus could be used for diagnosis and therapy of psychiatric conditions related to altered time perception.

This article investigates performance and user experience in Social Virtual Reality (SVR) targeting distributed, embodied, and immersive, face-to-face encounters. We demonstrate the close relationship between scalability, reproduction accuracy, and the resulting performance characteristics, as well as the impact of these characteristics on users co-located with larger groups of embodied virtual others. System scalability provides a variable number of co-located avatars and Al-controlled agents with a variety of different appearances, including realistic-looking virtual humans generated from photogrammetry scans. The article reports on how to meet the requirements of embodied SVR with today's technical off-the-shelf solutions and what to expect regarding features, performance, and potential limitations. Special care has been taken to achieve low latencies and sufficient frame rates necessary for reliable communication of embodied social signals. We propose a hybrid evaluation approach which coherently relates results from technical benchmarks to subjective ratings and which confirms required performance characteristics for the target scenario of larger distributed groups. A user-study reveals positive effects of an increasing number of co-located social companions on the quality of experience of virtual worlds, i.e., on presence, possibility of interaction, and co-presence. It also shows that variety in avatar/agent appearance might increase eeriness but might also stimulate an increased interest of participants about the environment.

This article presents an experiment exploring the possible impact of avatar's body part visibility on players' experience and performance using current Virtual Reality (VR) gaming platform capacities. In an action-based VR game, a player sees an avatar in first person perspective which is replicating his/her hand, head and body motion. In contrast to the expected outcome from non-game VR contexts, our results did not reveal significant differences with an avatar presenting an increasing number of visible body parts. The body ownership, immersion, emotional and cognitive involvements as well as the perceived control and difficulty were not improved with a more coherent virtual body. This tends to confirm the strong performance aspect of action-based games, whereby control efficiency and enemy awareness is paramount, and could overcome the perceptual, behavioural or emotional effects of avatar embodiment. Digital games are indeed prone to create an intense flow state typically reducing self-awareness, and focusing on the game completion and high performance achievements. However, further experiments with full-body tracking and different game types are necessary to confirm this trend. This research outcome motivates further analysis of the mutual influence of bottom-up and top-down factors of avatar embodiment causing psychophysical effects. In addition, it provides useful indications for VR game developers and researchers on possible effects and evaluation methods.

Classical reminiscence therapy has been shown to effectively enhance the stability of memory and identity in people with dementia. Typically, reminiscence therapy uses biography artifacts like photos and personal items and objects. Today, many of these artifacts are from the digital realm providing new options to adapt or even improve the purely analog therapy. In this work we propose a method to enhance reminiscence therapy by computer simulated biographic associations. Our approach provides assistance for associative reasoning on affective stimuli and thus enables access to biographic content so that no deliberate search is required. We develop a recommender model for mapping mental states to biographic content based on similarity. The system dynamically adapts its state and the depicted digital artifacts to the responses of the user. It is a first step towards an immersive reminiscence therapy which will incorporate associated stimuli on multiple channels to increase effectiveness. A preliminary study showed encouraging results concerning the usability of the system.

This paper presents a mixed reality tabletop role-playing game with a novel combination of interaction styles and gameplay mechanics. Our contribution extends previous approaches by abandoning the traditional turn-based gameplay in favor of simultaneous real-time interaction. The increased cognitive and physical load during the simultaneous control of multiple game characters is counteracted by two features: First, certain game characters are equipped with AI-driven capabilities to become semi-autonomous virtual agents. Second, (groups of) these agents can be instructed by high-level commands via a multimodal - speech and gesture - interface.

This paper introduces a low-cost framework capable of combining both real-time markerless face and body tracking for faithful avatar embodiment in Virtual Reality (VR). We discuss suitable hardware and software solutions and present a first prototype. This work lays the technological basis for further research on the importance of the appearance and behavioral realism of avatars, e.g., for the illusion of virtual body ownership, for social interactions in VR, as well as for VR entertainment applications (immersive games or movies).

In this paper, we compare a full body marker set with a reduced rigid body marker set supported by inverse kinematics. We measured system latency, illusion of virtual body ownership, and task load in an applied scenario for inducing acrophobia. While not showing a significant change in body ownership or task performance, results do show that latency and task load are reduced when using the rigid body inverse kinematics solution. The approach therefore has the potential to improve virtual reality experiences.

In this paper, we describe an experimental method to investigate the effects of reduced social information and behavioral channels in immersive virtual environments with full-body avatar embodiment. We compared physical-based and verbal-based social interactions in real world (RW) and virtual reality (VR). Participants were represented by abstract avatars that did not display gaze, facial expressions or social cues from appearance. Our results show significant differences in terms of presence and physical performance. However, differences in effectiveness in the verbal task were not present. Participants appear to efficiently compensate for missing social and behavioral cues by shifting their attentions to other behavioral channels.

This article presents a fully immersive portable low-cost Virtual Reality system to train classroom management skills. An instructor controls the simulation of a virtual classroom populated with 24 semi-autonomous virtual agents via a desktop-based graphical user interface (GUI). The GUI provides behavior control and trainee evaluation widgets alongside a non-immersive view of the class and the trainee. The trainee's interface uses an Head-Mounted Display (HMD) and earphones for output. A depth camera and the HMD's built-in motion sensors are used for tracking the trainee and for avatar animation. An initial evaluation of both interfaces confirms the system's usefulness, specifically its capability to successfully simulate critical aspects of classroom management.

This paper introduces a fake mirror system as a research tool to study the effect of avatar embodiment with non-visually immersive virtual environments. The system combines marker-less face and body tracking to animate the individual avatars seen in a stereoscopic display with a correct perspective projection. The display dimensions match typical dimensions of a real physical mirror and the animated avatars are rendered based on a geometrically correct reflection as expected from a real mirror including correct body and face animations. The first evaluation of the system reveals the high acceptance of the setup as well as a convincing illusion of a real mirror with different types of avatars.

This paper presents an exploratory experiment measuring the role of audio feedback on the illusion of virtual body ownership (IVBO) under non-immersive mixed reality (MR) settings with Human and Non-Human avatars. Our preliminary results revealed that all avatars elicited a similar level of IVBO, despite the addition of audio feedback.

In this paper, we investigate the impact of avatar anthropomorphism on the fear of heights, when using full body avatar embodiment under an immersive virtual reality (VR) setting. Clear differences could be found in perceived anthropomorphism, but preliminary results do not show differences in stress level between Human and Non-Human avatars, although a high level of perceived secureness was reported with Non-Human avatars.

Today's physics engines mainly simulate classical mechanics and rigid body dynamics, with some late advances also capable of simulating massive particle systems and some approximations of fluid dynamics. An accurate numerical simulation of complex nonmechanical processes in real time is beyond the state of the art in the respective fields. This paper illustrates an alternative approach to a purely numerical solution. It uses a semantic representation of physical properties and processes as well as a reasoning engine to model cause and effect between objects, based on their material properties. Classical collision detection is combined with semantic rules to model various physical processes, for example, in the areas of thermodynamics, electrodynamics, and fluid dynamics as well as chemical processes. Each process is broken down into fine-grained subprocesses capable of approximating continuous transitions with discretized state changes. Our system applies these high-level state descriptions to low-level value changes, which are directly mapped to a graphical representation of the scene. We demonstrate our framework's ability to support multiple complex, causally connected physical and chemical processes by simulating a Goldberg machine. Our performance benchmarks validate its scalability and potential application for entertainment or edutainment purposes.

In this paper we present a preliminary study of the impact of avatar realism on illusion of virtual body ownership (IVBO), when using a full body virtual mirror for fitness training. We evaluated three main types of user representation: realistic and non-realistic avatars as well as no avatar at all. Our results revealed that same-gender realistic human avatar elicited a slightly higher level of illusion and performance. However qualitative analysis of open questions revealed that the feeling of power was higher with non-realistic strong-looking avatars.

In this paper we present a novel experiment to explore the impact of avatar realism on the illusion of virtual body ownership (IVBO) in immersive virtual environments, with full-body avatar embodiment and freedom of movement. We evaluated four distinct avatars (a humanoid robot, a block-man, and both male and female human adult) presenting an increasing level of anthropomorphism in their detailed compositions Our results revealed that each avatar elicited a relatively high level of illusion. However both machine-like and cartoon-like avatars elicited an equivalent IVBO, slightly superior to the human-ones. A realistic human appearance is therefore not a critical top-down factor of IVBO, and could lead to an Uncanney Valley effect.

In this paper we present a study of the impact of avatar realism on user experience and performance in stressful immersive virtual environments. We evaluated a stressful and a stress-free environment with partial avatar embodiment under low (iconic) or high (photorealistic) visual fidelity conditions. An experiment with forty participants did not reveal any significant differences between both graphical versions. This first result represents an interesting finding since non realistic avatar and environment representations are faster and more economical to produce while requiring less computational resources.

Precise, accurate, fast, and low-latency motion tracking is a core requirement of real-time human-computer interfaces. The choices of tracking systems for a particular set of 3D interaction techniques are manifold. Hence, guidance in this task is greatly beneficial. In this paper, we propose to establish a set of canonical and simple game-based benchmarks for a potentially standardised comparison of tracking systems. The benchmarks focus on usability scores given reoccurring interaction tasks without requiring potentially missing, incomplete, or complex latency or accuracy raw measurements. Our first two benchmarks evaluate three tracking systems regarding motion-parallax and 3D object manipulation techniques. Our usability comparisons confirmed an expected advantage of low-latency/high-accuracy systems, while they also demonstrated that certain tracking systems perform better than suggested by previous measurements of their raw performances. This indicates that our approach provides an adequate replacement and improvement over the pure comparison of technical specifications. We believe our benchmarks could benefit the research community by facilitating a usability-based comparison of motion tracking systems.

Previous attempts at developing immersive versions of game engines have faced difficulties in achieving both overall high performance and preserving reusability of software developments. In this paper, we present a high-level VR middleware based on one of the most successful commercial game engines: the Unreal® Engine 3.0 (UE3). We describe a VR framework implemented as an extension to the Unreal® Development Kit (UDK) supporting CAVE"-like installations. Our approach relies on a distributed architecture reinforced by specific replication patterns to synchronize the user's point of view and interactions within a multi-screen installation. Our performance benchmarks indicated that our immersive port does not affect the game engine performance, even with complex real-time applications, such as fast-paced multiplayer First Person Shooter (FPS) games or high-resolution graphical environments with 2M+ polygons. A user study also demonstrated the capacity of our VR middleware to elicit high spatial presence while maintaining low cybersickness effects. With free distribution, we believe such a platform can support future Entertainment and VR research.

This paper describes an experiment comparinng immersive and non-immersive gaming using a state-of-the-art first person shooter game (FPS) in which we analyse user experience and performance through a combination of in-game metrics, questionaires and subjective reports. Our results show an overwhelming subjective preference for the immersive version despite a decrease in performance attributed to a more realistic aimming mechanism. Interaction metrics suggest that users took full advantage of the immmersive context rather than simply transposing their desktop gaming skills.

The Entertainment potential of Virtual Reality is yet to be fully realised.In recent years, this potential has been described through the Holodeck™ metaphor, without however addressing the issue of content creation and gameplay.Recent progress in Interactive Narrative technology makes it possible to envision immersive systems.Yet, little is known about the usability of such systems or which paradigms should be adopted for gameplay and interaction.We report user experiments carried out with a fully immersive Interactive Narrative system based on a CAVE-like system, which explore two interactivity paradigms for user involvement (Actor and Ghost).Our results confirm the potential of immersive Interactive Narratives in terms of performance but also of user acceptance.

Game programmers rely on artificial intelligence techniques to encode characters' behaviors initially specified by game designers. Although significant efforts have been made to assist their collaboration, the formalization of behaviors remains a time-consuming process during the early stages of game development. We propose an authoring tool allowing game designers to formalize, visualize, modify, and validate game level solutions in the form of automatically generated storyboards. This system uses planning techniques to produce a level solution consistent with gameplay constraints. The main planning agent corresponds to the player character, and the system uses the game actions as planning operators and level objectives as goals to plan the level solutions. Generated solutions are presented as 2-D storyboards similar to comic strips. We present in this paper the first version of a fully implemented prototype as well as examples of generated storyboards, adapted from the original design documents of the blockbuster game Hitman.

3D graphics systems increasingly rely on sophisticated event systems derived from collision detection mechanisms, which support the discretisation of Physics as well as high-level programming and scripting. By contrast, augmented reality systems have not yet adopted this approach. We describe the development of a high-level event system on top of the ARToolkit environment incorporating the ODE Physics engine. We first define a typology of events encompassing interactions between virtual objects as well as interactions involving markers. We then describe how these events can be recognised in real-time from elementary collisions detected by the ODE Physics engine. We conclude by discussing examples of high-level event recognitions and how they can support the development of applications.

The development of complex interactive 3D systems raises the need for representations supporting more abstract descriptions of world objects, their behaviour and the world dynamics. The inclusion of Artificial Intelligence representations and their use within 3D graphic worlds face both fundamental and technical issues due to the difference in representational logic between computer graphics and knowledge-based systems. We present a framework for such an integration illustrated by a first prototype.

In this paper, we describe a small-scale, yet complete, integration of a real-time immersive interactive storytelling system. While significant progress has been achieved in recent years on the individual component technologies of interactive storytelling, the main objective of this work is to investigate the concept of interactive storytelling in a fully immersive context. We describe each individual component of immersive interactive storytelling from a technical perspective. We have used a commercial game engine as a development environment, supporting real-time visualisation as well as the inclusion of Artificial Intelligence components controlling virtual actors. This visualisation engine has been ported to an immersive setting using dedicated software and hardware supporting real-time stereoscopic visualisation. The hardware platform is built around a 4-sided CAVE-like immersive display operated by a PC-cluster. The interactive storytelling engine is constituted by a planning system based on characters motivations and emotional states. The user can interact with the virtual world using multimodal interaction. We illustrate the system's behaviour on the implementation of excerpts from Madame Bovary, a classic XIXth century novel, and demonstrate the ability for the user to play the role of one of the characters and influence the unfolding of the story by his actions.

In this paper, we discuss how a cognitive concept, causality, can be used for the conceptual underpinning of Virtual Reality Art installations. Causality plays an important role in our construction of reality and, as such, it makes sense to use it as a principle to define VR experiences. We have developed a VR platform using cognitive data on causal perception to create artificial event co-occurrences in virtual worlds, which can be perceived as possible outcomes for user actions. After a preliminary validation of this technology by user experiments, it has been used to implement prototypes of artistic installations by two different artists. We describe the technical approach behind the elicitation of causal perception in virtual reality, and illustrate its use through the two artistic installations being developed with this new VR platform.

In this paper, we describe a new approach to the creation of virtual environments, which uses qualitative physics to implement object behaviour. We adopted Qualitative Process Theory as a qualitative reasoning formalism, due to its representational properties (e.g., its orientation towards process ontologies and its explicit formulation of process' pre-conditions). The system we describe is developed using a game engine and takes advantage of its event-based system to integrate qualitative process simulation in an interactive fashion. We use a virtual kitchen as a test environment. In this virtual world, we have implemented various behaviours: physical object behaviour, complex device behaviour (appliances) and "alternative" (i.e. non-realistic) behaviours, which can all be simulated in user real-time. After a presentation of the system architecture and its implementation, we discuss example results from the prototype. This approach has potential applications in simulation and training, as well as in entertainment and digital arts. This work also constitutes a test case for the integration of an Artificial Intelligence technique into 3D user interfaces.

We introduce a novel approach to the creation of Virtual Reality Art installations, which supports the design of alternative worlds, in which laws of Physics can be redefined to induce new user experiences. To implement this concept of "Alternative Reality", we have used Artificial Intelligence techniques to support the definition of the virtual environment behaviour, an approach inspired by Qualitative Reasoning systems. Besides the redefinition of physical laws, we have developed mechanisms for eliciting causal relations between events, as causality plays an important part in users' perception of virtual worlds. Our pilot installation is a CAVETM-like system incorporating a state-of-the-art computer game engine as visualisation software, which has-been ported to this immersive display. The event-based system underlying the game engine is used to bypass the native Physics engine and replace it with our Alternative Reality software. A first prototype has been fully implemented, the Alternative Reality modules totaling over 100,000 lines of C++ code. We present early results obtained with this approach, illustrated with examples taken from two artistic briefs, developed by digital artists associated to this research.

Virtual Reality Art involves the design of artificial worlds that offer new experiences to spectators. An important aspect for the development of VR Art installations is the principled definition of behaviour for the environment as a whole, which would facilitate experiments with alternative laws of physics, time, and causality. We describe the first results of an ongoing project dedicated to the development of software tools for the use of Intelligent Virtual Environments in VR Art. Using the architecture of a state-of-the-art game engine, we have developed Artificial Intelligence techniques that support the definition of alternative laws of physics. After discussing the principles behind alternative reality we describe two complementary modes of description for alternative behaviour: qualitative physics and causal simulation. This is illustrated by examples integrated into the virtual environment.