CEIG’09, San Sebastián, Sept. 9-11 (2009) C. Andújar and J. Lluch (Editors) © The Eurographics Association 2009. A Framework for Rendering, Simulation and Animation of Crowds N. Pelechano, B. Spanlang, A. Beacco Universitat Politècnica de Catalunya, Barcelona, Spain Abstract Real-time crowd simulation for virtual environment applications requires not only navigation and locomotion in large environments while avoiding obstacles and agents, but also rendering high quality 3D fully articulated fig- ures to enhance realism. In this paper, we present a framework for real-time simulation of crowds. The framework is composed of a Hardware Accelerated Character Animation Library (HALCA), a crowd simulation system that can handle large crowds with high densities (HiDAC), and an Animation Planning Mediator (APM) that bridges the gap between the global position of the agents given by HiDAC and the correct skeletal state so that each agent is rendered with natural locomotion in real-time. The main goal of this framework is to allow high quality visualization and animation of several hundred realistic looking characters (about 5000 polygons each) navigating virtual environments on a single display PC, a HMD (Head Mounted Display), or a CAVE system. Results of several applications on a number of platforms are pre- sented. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism – Animation; I.6.8 [Simulation and Modeling]: Types of Simulation – Animation. 1. Introduction Natural looking crowd simulation is necessary for appli- cations such as video games and training simulators. Natu- ral looking animations become even more important in immersive applications where a real participant can interact in real-time with characters in a virtual environment. If our goal is to be able to interact with relatively large number of agents, it is necessary that those agents perform natural path planning and animations, making sure that there is consistency between what we would expect in the virtual world from our experiences in the real world. In order to achieve visually appealing results it is neces- sary to integrate motion planners with motion synthesizers. Most crowd simulation systems focus on the path planning and local motion details of the agents while using a charac- ter animation library to render 3D fully articulated charac- ters playing a small set of animation clips. The main prob- lem that can be easily observed is that the characters have a very limited number of movements available and that con- straints such as ground contact points are not respected. Generating empathetic characters with realistic move- ments and responses to other virtual agents and obstacles in the environment can be very tedious work, since they usu- ally require large number of animation clips to be able to exhibit a large variety of movements. Being able to gener- ate synthesized motions from small sets of animation clips is thus of extreme relevance especially if we want to exhibit variety while following the requirements given by a crowd simulation module dealing with path planning and local motion. In this paper we present a framework for real-time crowd simulation which integrates a crowd simulation module that determines the position, velocity and orientation of each agent at every frame with a motion synthesizer that will guarantee smooth and natural looking animation for every agent. In order to integrate both modules we developed an Animation Planning Mediator which with the information