CEIG - Spanish Computer Graphics Conference (2014) , pp. 1–11 Pere-Pau Vázquez and Adolfo Muñoz (Editors) CAVAST The Crowd Animation, Visualization, and Simulation Testbed A. Beacco1 & N. Pelechano1 1Universitat Politècnica de Catalunya Abstract Simulation, animation and rendering of crowds has become an important part of real-time applications such as videogames. Virtual environments achieve higher realism when being populated by virtual crowds as opposed to appearing uninhabited. There has been a large amount of research on simulation, animation and rendering of crowds, but in most cases they seem to be treated separately as if the limitations in one area did not affect the others. At the end of the day the goal is to populate environments with as many characters as possible in real time, and it is of little use if one can for instance render thousands of characters in real time, but you cannot move more than a hundred due to a simulation bottleneck. The goal of our work is to provide a framework that lets the researcher focus on each of these topics at a time (simulation, animation, or rendering) and be able to explore and push the boundaries on one topic without being strongly limited by the other related issues. This paper presents therefore a new prototyping testbed for crowds that lets the researcher focus on one of these areas of research at a time without loosing sight of the others. We offer default representations, animation and simulation controllers for real time crowd simulation, that can easily be replaced or extended. Fully configurable level-of-detail for both rendering and simulation is also available. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Animation 1. Introduction straight forward. There are some commercial tools that pro- vide aids to simulate crowds, but in most cases there are lim- Crowds simulation [PAB08, TM13] is becoming more and itations that cannot be overcome, such as finding bottlenecks more important in computer applications such as building in a different area than the one you are researching on, thus evacuation planning, training, videogames, etc., with hun- pushing you from meeting real time constraints as we in- dreds or thousands of agents navigating in virtual environ- crease the size of the crowd. ments. Some of these applications, in order to offer complete interaction with the user, need to be run in real-time. In or- Due to the high computational needs of each of these three der to achieve natural looking crowds, the simulation needs areas individually, the process of integrating animation, sim- to exhibits natural behaviors, to have characters that are ani- ulation and rendering of real time crowds, often presents mated with smooth and realistic looking walking styles, and trade-offs between accuracy and quality of results. As we also that the rendering does not exhibit any noticeable arti- will describe in this paper, these three areas cannot be treated facts. When simulating large numbers of characters the goal in a completely separated way as most current tools do, since is usually to produce both the best local motion and anima- there is a strong overlapping between them, and users need tion, minimizing the awkwardness of movements and elimi- to be aware of this when setting up a simulation (see Figure nating or lessening any visual artifacts. 1). For example, we cannot increase the number of anima- tions easily if we are rendering exclusively with impostors. Achieving simulation, animation and rendering of the crowd in real-time becomes thus a major challenge. Al- Currently it is not easy to find a real time framework that though each of these areas has been studied separately and allows you to easily work on one of these areas. If for exam- improvements have been presented in the literature, the in- ple you want to focus your research on a new steering behav- tegration of these three areas in one real-time system is not ior, you will start and do most of your experiments by visual- c The Eurographics Association 2014. A. Beacco & N. Pelechano / CAVAST: The Crowd Animation, Visualization, and Simulation Testbed 2. Related Work There are some well known commercial tools for model- ing and simulation software such as 3D Studio Max [Auta], Maya [Autc] or Blender [BF] that allow us to add crowds to a virtual scene. There exist also many plug-ins for these packages that can be used to extend their basic features. For example Golaem Crowd [Goa14] is a powerful plug- in for Maya [Autc]. Golaem Crowd is a complete commer- cial package for crowd authoring, including tools for placing crowds, create behaviors, animate characters, create diver- sity of agents, and render the resulting simulations. Although Figure 1: Simulation, Animation and Rendering of Crowds they offer some real-time previsualizations in order to help are three overlapping research areas dependent on each the artists creating new crowds and defining behaviors, their other which are continuously interacting. target is mostly the movie industry producing high quality offline renders. It is not as much a research platform as it is a commercial production tool. Also in the movie industry, a major competitor is Massive [Mas14], an expensive crowd izing a set of circles or cylinders representing your different simulation tool that has been used in many films. agents. But in the end you would like to see your results rep- resented by 3D animated characters. The switch from having In the crowd simulation literature there are some steering 2D circles to fully articulated 3D characters in real time can behavior libraries such as OpenSteer [Rey], which also in- be very time consuming. Or for example, your research in- cludes a demo software for simple visualizations of the im- terest may be focused on implementing a new representation plemented steering behaviors through simple 2D representa- for rendering thousands of characters. Once you achieve real tions. We can also find SteerSuite [SKFR09], a flexible but time visualization of such a huge amount of characters, you easy-to-use set of tools, libraries, and test cases for steering do not want to end up displaying them in a grid formation or behaviors. The spirit of SteerSuite [SKFR09] was to make it giving the agents random positions where they stay in place. practical and easy-to-use, yet flexible and forward-looking, Instead, one would want them to be animated and moving to challenge researchers and developers to advance the state in a virtual environment, if possible with collision avoidance of the art in steering. Although their simulation part is very and natural animation. Again this is not straight forward in complete, there is not such thing as animated 3D characters current frameworks. And finally, the same applies for the an- for visualization of the simulated crowds. imation field, if you are defining new animation controllers For character animation, there is just a few libraries that for 3D characters, you would like to test them with hundreds we can easily include in any C++ project. A commercial ex- of characters moving around a virtual environment with re- ample would be Granny 3D [RGT], which includes a com- alistic rendering. plete animation system including features such as blend- In this paper, we present a novel framework that embeds graphs, character behavior, events synchronization or pro- these three elements: Simulation, Animation and Rendering cedural IK. But again it is a solution for artist and for com- of crowds. Each of them presented in an independent-but- mercial products, not for doing research. Some free solu- linked modular way. The final tool becomes then a proto- tions are Animadead [But], a skeletal animation library with typing testbed for crowds that allows the researcher to fo- basic functionalities, or Cal3D [Cal] another skeletal anima- cus on one of these parts at a time without loosing sight of tion library which also includes an animation mixer and in- the other two. This tool could also be very handy for in- tegrates morph targets. The Hardware Accelerated Library troducing crowd simulation in the classroom. Our bundle for Character Animation, HALCA [Spa], extends the Cal3D includes some basic resources such as character models, li- library to include new features such as GLSL shaders sup- braries and implemented controllers interfaces, which allows port, morph animations, hardware accelerated morph targets the researcher to have a basic crowd simulation engine to (blend shapes), dual quaternion skin shaders, JPEG texture get started, and to be able to focus exclusively in a particu- files, direct joint manipulation and other additions. The FBX lar area or research. Our module also lets the researcher to SDK [Autb] is another library allowing to read FBX files, have communication and interaction between these areas, if which is a widely used and extended format for character he desires to treat some of them in a more dependent fashion. modeling and animation. The API includes some skinning We offer default representations, animation and simulation examples, but you should still program your animation li- interfaces and controllers in a modular way, that can easily brary to use FBX models imported with it. Our framework be extended with your new research work. We also include currently offers HALCA [Spa] as the animation library, but a fully configurable system of level-of-detail for animation, the user can create its own characters based on any other li- visualization and simulation. brary. c The Eurographics Association 2014. A. Beacco & N. Pelechano / CAVAST: The Crowd Animation, Visualization, and Simulation Testbed Figure 2: Diagram with a rough overview of the classes in CAVAST. In the case of applications that require real time crowd Unity [Uni14] you might be restricted to a fixed renderer and simulation, such as video games, there are several tools to its animation system, unless you implement your own us- commonly used both commercial (Unreal [Epi14], Unity ing plug-ins.