Christopher Peters

Bottom-up visual attention for virtual human animation

We present a system for the automatic generation of bottom-up visual attention behaviours in virtual humans. Bottom-up attention refers to the way in which the environment solicits ones attention without regard to task-level goals. Our framework is based on the interactions of multiple components: a synthetic vision system for perceiving the virtual world, a model of bottom-up attention for early visual processing of perceived stimuli, a memory system for the storage of previously sensed data and a gaze controller for the generation of resultant behaviours. Our aim is to provide a feeling of presence in inhabited virtual environments by endowing agents with the ability to pay attention to their surroundings.

Levels of Detail for Crowds and Groups.

Work on levels of detail for human simulation has occurred mainly on a geometrical level, either by reducing the numbers of polygons representing a virtual human, or replacing them with a two‐dimensional imposter. Approaches that reduce the complexity of motions generated have also been proposed. In this paper, we describe ongoing development of a framework for Adaptive Level Of Detail for Human Animation (ALOHA), which incorporates levels of detail for not only geometry and motion, but also includes a complexity gradient for natural behaviour, both conversational and social.

Modeling Groups of Plausible Virtual Pedestrians

In a proposed methodology for modeling dynamic crowd scenarios, a video corpus informs the modeling process, after which the resultant animations undergo perception-based evaluation. The aim is to improve the crowds visual plausibility rather than the simulations correctness. A real-life crowd animation system demonstrates the methodologys practical application.

Synthetic Vision and Memory for Autonomous Virtual Humans

A memory model based on ``stage theory, an influential concept of memory from the field of cognitive psychology,is presented for application to autonomous virtual humans. The virtual human senses external stimuli througha synthetic vision system. The vision system incorporates multiple modes of vision in order to accommodate aperceptual attention approach. The memory model is used to store perceived and attended object information atdifferent stages in a filtering process. The methods outlined in this paper have applications in any area wheresimulation‐based agents are used: training, entertainment, ergonomics and military simulations to name but afew.

Perceptual effects of scene context and viewpoint for virtual pedestrian crowds

In this article, we evaluate the effects of position, orientation, and camera viewpoint on the plausibility of pedestrian formations. In a set of three perceptual studies, we investigated how humans perceive characteristics of virtual crowds in static scenes reconstructed from annotated still images, where the orientations and positions of the individuals have been modified. We found that by applying rules based on the contextual information of the scene, we improved the perceived realism of the crowd formations when compared to random formations. We also examined the effect of camera viewpoint on the plausibility of virtual pedestrian scenes, and we found that an eye-level viewpoint is more effective for disguising random behaviors, while a canonical viewpoint results in these behaviors being perceived as less realistic than an isometric or top-down viewpoint. Results from these studies can help in the creation of virtual crowds, such as computer graphics pedestrian models or architectural scenes, and identify situations when users perception is less accurate.

Attention-driven eye gaze and blinking for virtual humans

Gaze and blinking have recently been considered for application to social interactions among computer characters based on emotional states. In this sketch, we present improvements to a gaze controller in terms of both the contributions by the joints involved in the motion and also by a closer analysis of the role of blinking and blink synchronisation in the realism of the final animation. Unlike previous approaches, our controllers are driven by internal character states derived from, among other factors, a model of visual attention and short-term memory. Given a position to look at and taking into account internal state information such as an agent’s interests, motivation and memory, the gaze and blink controllers are charged with the responsibility of executing an appropriate gaze motion in an expressive manner.

Perceptual evaluation of position and orientation context rules for pedestrian formations

In this paper, we evaluate the effects of position and orientation on the plausibility of pedestrian formations. In a perceptual study we investigated how humans perceive characteristics of virtual crowds in static scenes reconstructed from annotated still images where the orientations and positions of the individuals have been modified. We found that by applying rules based on the contextual information of the scene, such as the type of scene being portrayed, the presence of nearby individuals and objects and the constraints of the walking areas in the scene, we improved the perceived realism of the crowd formations. Results from this study can help in the creation of virtual crowds, such as computer graphics pedestrian models or architectural scenes.