Simulating Gait and Structural Effects of Aging for Improved Diversity in Virtual Crowds Chathika Gunaratne 1 , Prasad Wimalaratne 2 University of Colombo School of Computing Colombo 7, Sri Lanka 1 chathikagunaratne@gmail.com, 2 spw@ucsc.cmb.ac.lk Abstract— In real human crowds, diversification is caused by many factors such as gender, age, skin color, clothing, walking style, psychology etc., yet most crowd simulation systems rely only on appearance related variables for diversification. This research explores improving crowd diversity by simulating the biomechanical effects of aging in humans within crowd characters. Simulated characters were reprogrammed to be able to predict their behavior through an aging parameter predictor using support vector regression respective to their age. Data from gerontology studies recording spinal curvature and walking pattern deterioration with age were used for training. A spatial diversity algorithm was designed and implemented to distribute the resulting variants evenly among each other. Evaluations were conducted to gauge the impact on the diversification of the crowd simulation. The results prove that simulating posture and walking pattern deterioration in older characters does significantly improve biomechanical diversity within a virtual human crowd. Keywords- Simulation; Crowd Simulation; Virtual Characters; Aging I. INTRODUCTION Virtual crowds of autonomous agents are extensively used in a variety of application domains including video games, films, psychology and operational research for the past couple of decades. An important factor contributing to the degree of realism of crowd simulation is the diversity between characters within it. If users tend to identify cloned characters within the crowd it will lead to a decline in the realism of simulation. Diversification of individuals within real human crowds can be attributed to many factors such as gender, age, skin color, clothing, walking style, level of aggression etc. Out of these attributes, it can be seen that most crowd simulation systems prefer to use clothing, skin color and other appearance related variables to make characters seem less similar to each other [1]. This paper explores the possibility of improving crowd diversity by simulating the biomechanical effects of aging in real humans within virtual characters, i.e. deterioration of posture and gait pattern with progressing age. Proving that simulating the biomechanical effects of aging leads to significant improvement in character realism and crowd diversity is the main aim of this research. The goal is to have characters at various stages of postural and locomotion deterioration at any given time. This study focuses on: • Discovering the significance of simulating the postural/structural effects of aging on character realism. • Discovering the significance of simulating the locomotion (walking pattern) changes due to aging on character realism. • Exploring the possibility of improving crowd diversity by having characters at different ages and displaying different states of biomechanical deterioration. This paper presents a model that can both generate age- able characters and also spatially disperse similar characters further apart within the crowd. Characters within the crowd are made able to age dynamically with progression of time and when the simulation speed is increased the biomechanical deterioration should be visible with progression of time. The implemented age-able characters use support vector regression based predictors to predict their current postural and locomotion parameters in accordance to their age. Additionally, a local similarity minimization algorithm has been used to distribute similar agents further apart from each other. Finally, three user evaluation experiments have been conducted to study the impact of this model on users’ perception of crowd diversity. II. RELATED WORK A. Biomechanical effects of Aging The effects of aging in humans are vast and can be classified into three: facial/skin changes due to age, biomechanical deterioration and psychological changes. This study focuses on the biomechanical changes that occur with age. 1) Gait changes Biomechanical changes include changes in gait pattern brought about by frailty, spinal kyphosis and a variety of other factors. Many studies have been conducted to study these changes in both clinical and pedestrian environments, for the purposes of physiological rehabilitation, traffic light timing at pedestrian crossings etc. Human gait testing can vary from simple speed tests to more complicated structured tests such as the Timed Up and Go test carried out by Steffen et al [2]. 2013 10th International Conference Computer Graphics, Imaging and Visualization 978-0-7695-5051-0/13 $26.00 © 2013 IEEE DOI 10.1109/CGIV.2013.13 17