Level of Detail (LoD) techniques for real-time... In this paper, we are particularly interested in the problem of realistic collision simulation in scenes where large numbers of objects are colliding and processing must occur in real-time. An interruptible and therefore degradable collision handling mechanism is used and the perceptual impact of this degradation is explored. We look for ways in which we can optimise the realism of such simulations and describe a series of psychophysical experiments that investigated different factors affecting collision perception, including eccentricity, separation, distractors, causality and accuracy of physical response. Finally, strategies for incorporating these factors into a perceptually adaptive real-time simulation of large numbers of visually similar objects are presented.

Related perceptual, motor, and cognitive performances were examined to reveal the accuracy of the properties of action spontaneously represented when mentally simulating moving one's hand. The kinematic configuration of the body represented and transformed in mental simulations was not fixed or canonical but corresponded to one's current configuration. Mental simulation time mimicked movement time for natural efficient movement from a posture midway between each of the hand's joint limits into many other postures. Equal time was required for simulated and real movements into more common, comfortable postures; shorter but proportional time was required for simulated movement than real movement into less common postures that involved longer trajectories, coordinated activity at more joints, motion near extremes of joint limits, and uncomfortable kinesthetic sensations. The findings suggest that sensorimotor structures support mental simulations of actions. Humans can envision an object, scene, or event and then inspect the mental representation in a manner that mimics or reflects real perceptual-motor performance (e.g., Craik,

In this chapter, we will discuss the usefulness of eye-tracking for computer applications that attempt to render simulations at interactive rates.

Many human activities require precise judgments about the physical properties and dynamics of multiple objects. Classic work suggests that people’s intuitive models of physics are relatively poor and error-prone, based on highly simplified heuristics that apply only in special cases or incorrect general principles (e.g., impetus instead of momentum). These conclusions seem at odds with the breadth and sophistication of naive physical reasoning in real-world situations. Our work measures the boundaries of people’s physical reasoning and tests the richness of intuitive physics knowledge in more complex scenes. We asked participants to make quantitative judgments about stability and other physical properties of virtual 3D towers. We found their judgments correlated highly with a model observer that uses simulations based on realistic physical dynamics and sampling-based approximate probabilistic inference to efficiently and accurately estimate these properties. Several alternative heuristic accounts provide substantially worse fits. Keywords: intuitive physics, dynamics, perception, model

Abstract While many of the existing velocity control techniques are well designed, the techniques are often applicationspecific, making it difficult to compare their effectiveness. In this paper, we evaluate five known velocity control techniques using the same experimental settings. We compare the techniques based on the assumption that a good travel technique should be easy to learn and easy to use, should cause the user to have few collisions with the VE, should allow the user to complete tasks faster, and should promote better recollection of the environment afterwards. In our experiments, we ask twenty users to use each velocity control technique to navigate through virtual corridors while performing information-gathering tasks. In all cases, the users use pointing to indicate the direction of travel. We then measure the users ’ ability to recollect the information they see in the VE, as well as how much time they spend in the VE and how often they collide with the virtual walls. After each

The behaviour of objects in the physical world is described by Newtonian mechanics, using dynamic concepts such as force and mass. However, it has been reported that many people have intuitive preconceptions concerning mechanical events that, although incorrect according to Newtonian mechanics, are highly stable and widespread. 3 Profitt and Gilden showed that people use only one dimension of information when making dynamical judgements. 6 Therefore, when a dynamic event involves more than one dimension of information such as velocity and rotation (i.e. an extended body motion as opposed to a particle which has only one dimension of information), humans are less able to correctly identify anomalous physical behaviour. They also discovered that judgements about collisions were made based on heuristics and that people are influenced by kinematic data, such as velocity after impact and the way that the colliding objects ricochet. 4