Populating 3D Cities: a True Challenge

In this paper, we describe how we can model crowds in real-time using dynamic meshes, static meshes andimpostors. Techniques to introduce variety in crowds including colors, shapes, textures, individualanimation, individualized path-planning, simple and complex accessories are explained. We also present ahybrid architecture to handle the path planning of thousands of pedestrians in real time, while ensuringdynamic collision avoidance. Several behavioral aspects are presented as gaze control, group behaviour, aswell as the specific technique of crowd patches

Populating 3D Cities: A True Challenge

In this paper, we describe how we can model crowds in real-time using dynamic meshes, static meshes andimpostors. Techniques to introduce variety in crowds including colors, shapes, textures, individualanimation, individualized path-planning, simple and complex accessories are explained. We also present ahybrid architecture to handle the path planning of thousands of pedestrians in real time, while ensuringdynamic collision avoidance. Several behavioral aspects are presented as gaze control, group behaviour, aswell as the specific technique of crowd patches

Target eccentricity effects for defensive responses

Defensive actions involving goal-directed responses to visual stimuli presented in different parts of the viewing field commonly include movements either toward (TOWARD) or away from (AWAY) the actual stimulus. One can categorize the type of defensive movements by outcome or the level of stimulus-response (S-R) compatibility, where a congruent response corresponds to a response in the TOWARD condition and an incongruent response corresponds to a response in the AWAY condition. In an effort to better understand defensive responses, which have received less attention in the literature than offensive movements regardless of their importance in combative situations, we studied the responses of quick yaw head rotations in the TOWARD and AWAY conditions to visual stimuli presented in different parts of the viewing field. In the first experiment (chapter 2) we examined the test-retest reliability of the primary and secondary measures associated with the quick yaw head rotations. After achieving an acceptable level of reliability for most measures, we investigated the effects of S-R compatibility and target eccentricity on the primary measures of reaction time of head rotation (RT) and activity of the sternocleidomastoid muscles of the neck (premotor RT) and the secondary measures of movement time, peak velocity, head excursion and the electromechanical delay for yaw head rotations (chapter 3). We found an increase in RT and premotor RT for yaw head rotations with large increases in visual field target eccentricity and involving incongruent responses observed in the AWAY condition. In chapter 4 we examined the effects of practice in the TOWARD or AWAY condition on performances in both conditions. We observed a shorter RT and premotor RT after 6 days of practice (over 2 weeks), regardless of condition practiced or of performance. Most subjects who practiced in the TOWARD condition produced greater decreases in RT and premotor RT for the TOWARD condition and most subjects who practiced in the AWAY condition produced greater decreases in RT and premotor RT for the AWAY condition. These data also suggest faster reactions in response to stimuli in the central visual field occur with practice. These results suggest reactions will be slowest for responses to objects in the far peripheral visual field and when trying to avoid object contact. RT and premotor RT at each eccentricity and for each condition can definitely improve with practice. The present results also provide small but potential added benefits for specificity of condition training. The parallel findings for RT and premotor RT suggest that outcomes observed for quick yaw head rotation RTs were primarily due to changes in neural processing time

The Influence of the Cervical Musculature, Visual Performance, and Anticipation on Head Impact Severity in High School and Collegiate Football

Context: Athletes with weaker, smaller, and less stiff cervical musculature; diminished visual performance; and that do not anticipate an oncoming collision are thought to be more likely to experience rapid head acceleration during collision. Objective: To compare the odds of sustaining higher magnitude head impacts between athletes with higher and lower performance on cervical characteristic and visual performance measures and to compare head impact magnitudes between anticipated and unanticipated collisions. Participants: Forty-nine high school and collegiate football players. Interventions: Participants completed the cervical testing protocol and visual performance assessment prior to the season. Video footage of on-field collisions was analyzed to determine each player's level of anticipation at the time of head impact. Head impact biomechanics were captured at each practice and game. Main Outcome Measures: Cervical muscle strength, size, and stiffness, visual performance measures, level of anticipation, and head impact biomechanical measures. Results: Football players with greater cervical stiffness had reduced odds of sustaining higher magnitude head impacts, rather than head impacts in the 1st quartile, compared to players with less cervical stiffness. Surprisingly, players with stronger and larger cervical musculature had increased odds of sustaining higher magnitude head impacts, rather than head impacts in the 1st quartile, compared to players with weaker and smaller cervical musculature. Players with better near-far quickness, target capture, and reaction time performance had increased odds of sustaining higher magnitude head impacts, rather than head impacts in the 1st quartile. Head impact biomechanical measures did not differ between anticipated and unanticipated collisions. Conclusions: Neuromuscular training aimed at enhancing cervical muscle stiffness may be useful in reducing the magnitude of head impacts sustained while playing football. The results of this study do not support the theory that players with stronger and larger cervical musculature are better able to mitigate head impact severity. Vision and level of anticipation may play less of a role than expected for protecting against higher magnitude head impacts among high school football players. In summary, cervical stiffness plays a role in mitigating head impact severity, but the roles of cervical strength, visual performance, and level of anticipation need further study.Doctor of Philosoph