Papers about Agent's Expression

This paper presents two attempts in integrating attentiveness into a virtual quiz agent in the situation when multiple game participants present. One of them features an utterance strategy to determine when and whom to talk to among the participants. The other one features a SVM (support vector machine) triggered transition state model of the agent's attitude toward the participants in expressing observable behaviors. Both of them are driven by timings determined on video and audio... Read more

Coming to open domain dialog it is still unrealistic to implement needed knowledge resources and dialog skills linguistically. Since the Non Player Characters (NPC) in our NPC Engine should be capable of open conversation we decided to use an Artificial Intelligence Markup Language (AIML) [1] chatbot as a first workaround. However AIML chatbots are not linguistically motivated, they use surface structures in tradition of Weizenbaums ELIZA [2], wherefore they do have too many shortcomings to... Read more

Virtual humans are employed in many interactive applications, including (serious) games. Their motion should be natural and allow interaction with its surroundings and other (virtual) humans in real time. Physical controllers offer physical realism and (physical) interaction with the environment. Because they typically act on a selected set of joints, it is hard to evaluate their naturalness in isolation. We propose to augment the motion steered by such a controller with motion capture, using a... Read more

In this paper, a new low-dimensional motion model that can parameterize human motion style is presented. Based on this model, a human motion synthesis approach by using constrainted optimization in a low-dimensional space is proposed. We define a new inverse kinematics solver in this low-dimensional space to generate the required motions meeting user-defined space constraints at key-frames. Our approach can also allow users to edit motion style explicitly by specifying the style parameter. The experimental... Read more

This paper presents an architecture for an intelligent virtual agent that imitates human drumming behaviour. Through imitation, the agent models the user-specific variations that constitute the "groove" of the drummer. The architecture comprises a motor system that imitates arm movements of a human drummer, and a sound system that produces the sound of the human playing style. The presence of a sound system alleviates the need to use physical models that will create sound when... Read more

Basic communication and coordination mechanisms of human social interaction are assumed to be mediated by perception-action links. These links ground the observation and understanding of others in one's own action generation system, as evidenced by immediate motor resonances to perceived behavior. We present a model to endow virtual embodied agents with similar properties of embodied perception. With a focus of hand-arm gesture, the model comprises hierarchical levels of motor representation (commands, programs, schemas) that are... Read more

Recent studies have shown that virtual humans can facilitate social interactions among people who have difficulty in forming social bonds or help develop their social skills by interaction with virtual practice. Virtual human research tends to focus exclusively on appearance or behavior in assessing agent effectiveness, whereas other studies of human social interaction emphasize aspects of the social context, such as anticipated future interaction (AFI) which has been implicated as a key moderator of people's... Read more

Expressing spatial information with iconic gestures is abundant in human communication and requires to transform a referent representation into resembling gestural form. This task is challenging as the mapping is determined by the visuo-spatial features of the referent, the overall discourse context as well as concomitant speech, and its outcome varies considerably across different speakers. We present a framework, GNetIc, that combines data-driven with model-based techniques to model the generation of iconic gestures with Bayesian... Read more

For simulating communicative behavior, realistic appearance and plausible behavior is important. Postures and mimics also reflect emotional behavior. There exist various models of emotion, like the psycho-evolutionary theory developed by Plutchik [1], or Ekman's FACS. But most models are only suited for muscular expressions. A more unattended field however, also in graphics, is the change in color. Also, other physiological symptoms like crying are left unconsidered. Read more

Authoring the AI for non-player characters (NPCs) in modern video games is an increasingly complex task. Designers and programmers must collaborate to resolve a tension between believable agents with emergent behaviours and scripted story lines. Behaviour trees (BTs) have been proposed as an expressive mechanism that let designers create complex behaviours along the lines of the story they want to tell. However, BTs are still too complex for non-programmers. In this paper, we propose the... Read more