The Impact of a Character Posture Model on the Communication of Affect in an Immersive Virtual Environment

This paper presents the quantitative and qualitative findings from an experiment designed to evaluate a developing model of affective postures for full-body virtual characters in immersive virtual environments (IVEs). Forty-nine participants were each requested to explore a virtual environment by asking two virtual characters for instructions. The participants used a CAVE-like system to explore the environment. Participant responses and their impression of the virtual characters were evaluated through a wide variety of both quantitative and qualitative methods. Combining a controlled experimental approach with various data-collection methods provided a number of advantages such as providing a reason to the quantitative results. The quantitative results indicate that posture plays an important role in the communication of affect by virtual characters. The qualitative findings indicated that participants attribute a variety of psychological states to the behavioral cues displayed by virtual characters. In addition, participants tended to interpret the social context portrayed by the virtual characters in a holistic manner. This suggests that one aspect of the virtual scene colors the perception of the whole social context portrayed by the virtual characters. We conclude by discussing the importance of designing holistically congruent virtual characters especially in immersive settings

Life-Sized Audiovisual Spatial Social Scenes with Multiple Characters: MARC & SMART-I²

International audienceWith the increasing use of virtual characters in virtual and mixed reality settings, the coordination of realism in audiovisual rendering and expressive virtual characters becomes a key issue. In this paper we introduce a new system combining two systems for tackling the issue of realism and high quality in audiovisual rendering and life-sized expressive characters. The goal of the resulting SMART-MARC platform is to investigate the impact of realism on multiple levels: spatial audiovisual rendering of a scene, appearance and expressive behaviors of virtual characters. Potential interactive applications include mediated communication in virtual worlds, therapy, game, arts and elearning. Future experimental studies will focus on 3D audio/visual coherence, social perception and ecologically valid interaction scenes

An Extendable Multiagent Model for Behavioural Animation

This paper presents a framework for visually simulating the behaviour of actors in virtual environments. In principle, the environmental interaction follows a cyclic processing of perception, decision, and action. As natural life-forms perceive their environment by active sensing, our approach also tends to let the artificial actor actively sense the virtual world. This allows us to place the characters in non-preprocessed virtual dynamic environments, what we call generic environments. A main aspect within our framework is the strict distinction between a behaviour pattern, that we term model, and its instances, named characters, which use the pattern. This allows them sharing one or more behaviour models. Low-level tasks like sensing or acting are took over by so called subagents, which are subordinated modules extendedly plugged in the character. In a demonstration we exemplarily show the application of our framework. We place the same character in different environments and let it climb and descend stairs, ramps and hills autonomously. Additionally the reactiveness for moving objects is tested. In future, this approach shall go into action for a simulation of an urban environment

Hide and sneak: story generation with characters that perceive and assume

We describe the design of a perception system for the characters in the Virtual Storyteller (VST), a character-centric story generation system. Previously, these characters were omniscient; stories involving sneaking and deception could not be generated. To remedy this, we limited the characters' visual perception using simple rules. We enabled the characters to make assumptions about the story world, so they can plan toward goals in spite of incomplete knowledge. Using the distinction between the character and actor roles of agents in the VST, we can use the assumptions to steer the story plot

The uncanny valley of a virtual animal.

Virtual robots, including virtual animals, are expected to play a major role within affective and aesthetic interfaces, serious games, video instruction, and the personalization of educational instruction. Their actual impact, however, will very much depend on user perception of virtual characters as the uncanny valley hypothesis has shown that the design of virtual characters determines user experiences. In this article, we investigated whether the uncanny valley effect, which has already been found for the human-like appearance of virtual characters, can also be found for animal-like appearances. We conducted an online study (N = 163) in which six different animal designs were evaluated in terms of the following properties: familiarity, commonality, naturalness, attractiveness, interestingness, and animateness. The study participants differed in age (under 10–60 years) and origin (Europe, Asia, North America, and South America). For the evaluation of the results, we ranked the animal-likeness of the character using both expert opinion and participant judgments. Next to that, we investigated the effect of movement and morbidity. The results confirm the existence of the uncanny valley effect for virtual animals, especially with respect to familiarity and commonality, for both still and moving images. The effect was particularly pronounced for morbid images. For naturalness and attractiveness, the effect was only present in the expert-based ranking, but not in the participant-based ranking. No uncanny valley effect was detected for interestingness and animateness. This investigation revealed that the appearance of virtual animals directly affects user perception and thus, presumably, impacts user experience when used in applied settings

Images that we should not see. The issue of non-perceptual attitudes from film to virtual reality

This paper casts film experience as a sort of disembodied perception. I will show how this experience can be manipulated and altered in order to approximate to mental states of fictional characters, in particular embodied perception, memory and imagination. I will acknowledge that film experience can approximate to non-perceptual attitudes such as memory and imagination much better than the experience elicited by theater. Yet, I will contend, film experience cannot emulate the phenomenology of non-perceptual attitudes since it remains a sort of disembodied perception even when it is manipulated by filmmakers in order to approximate memory states or imaginative states of fictional characters. Finally, I will argue that virtual reality, in virtue of both its proximity to embodied perception and its potential for manipulation, is, in principle, in a better position than film when it comes to trying to emulate non-perceptual attitudes such as memory and imagination

An Eye Gaze Model for Controlling the Display of Social Status in Believable Virtual Humans

Abstract—Designing highly believable characters remains a major concern within digital games. Matching a chosen personality and other dramatic qualities to displayed behavior is an important part of improving overall believability. Gaze is a critical component of social exchanges and serves to make characters engaging or aloof, as well as to establish character’s role in a conversation. In this paper, we investigate the communication of status related social signals by means of a virtual human’s eye gaze. We constructed a cross-domain verbal-conceptual computational model of gaze for virtual humans to facilitate the display of social status. We describe the validation of the model’s parameters, including the length of eye contact and gazes, movement velocity, equilibrium response, and head and body posture. In a first set of studies, conducted on Amazon Mechanical Turk using prerecorded video clips of animated characters, we found statistically significant differences in how the characters’ status was rated based on the variation in social status. In a second step based on these empirical findings, we designed an interactive system that incorporates dynamic eye tracking and spoken dialog, along with real-time control of a virtual character. We evaluated the model using a presential, interactive scenario of a simulated hiring interview. Corroborating our previous finding, the interactive study yielded significant differences in perception of status were found (p = .046). Thus, we believe status is an important aspect of dramatic believability, and accordingly, this paper presents our social eye gaze model for realistic procedurally animated characters and shows its efficacy. Index Terms—procedural animation, believable characters, virtual human, gaze, social interaction, nonverbal behaviour, video game

Dynamic Facial Expression of Emotion Made Easy

Facial emotion expression for virtual characters is used in a wide variety of areas. Often, the primary reason to use emotion expression is not to study emotion expression generation per se, but to use emotion expression in an application or research project. What is then needed is an easy to use and flexible, but also validated mechanism to do so. In this report we present such a mechanism. It enables developers to build virtual characters with dynamic affective facial expressions. The mechanism is based on Facial Action Coding. It is easy to implement, and code is available for download. To show the validity of the expressions generated with the mechanism we tested the recognition accuracy for 6 basic emotions (joy, anger, sadness, surprise, disgust, fear) and 4 blend emotions (enthusiastic, furious, frustrated, and evil). Additionally we investigated the effect of VC distance (z-coordinate), the effect of the VC's face morphology (male vs. female), the effect of a lateral versus a frontal presentation of the expression, and the effect of intensity of the expression. Participants (n=19, Western and Asian subjects) rated the intensity of each expression for each condition (within subject setup) in a non forced choice manner. All of the basic emotions were uniquely perceived as such. Further, the blends and confusion details of basic emotions are compatible with findings in psychology

Keynote Talk 2: Social and Perceptual Fidelity of Avatars and Autonomous Agents in Virtual Reality

Advances in display, computing and sensor technologies have led to a revival of interest and excitement surrounding immersive virtual reality. Here, on the cusp of the arrival of practical and affordable virtual reality technology, are open questions regarding the factors that contribute to compelling and immersive virtual worlds. In order for virtual reality to be useful as a tool for use in training, education, communication, research, content-creation and entertainment, we must understand the degree to which the perception of the virtual environment and virtual characters resembles perception of the real world. Relatedly, virtual reality\u27s utility in these contexts demands evidence that goal-directed behaviors and interpersonal interactions in virtual reality mimic real-world actions and that learning in one domain transfers to the other. In particular, providing the virtual reality user with a compelling sense of self and co-presence with virtual others has implications not just for creating convincing social environments but even for conveying the intended sense of scale and space in virtual environments. This presentation discusses the importance and challenges involved in creating and depicting interactive avatars representing both human and computer-controlled agents. Special attention will be paid to the use of computer-controlled avatars to both investigate interpersonal processes and behaviors and to improve the fidelity and naturalism of these autonomous agents. Biographical sketch: Benjamin R. Kunz received his Ph.D. in Cognitive Psychology from the University of Utah in 2010. He is now an assistant professor in the Department of Psychology at the University of Dayton with research interests in visual-spatial perception and action in real and virtual environments, embodied cognition and the body schema, and social influences on spatial cognition