Interactive level of detail control for film quality crowd animation International Conference on Control, Automation and Systems 2008 Oct , 2008 in COEX, Seoul, Korea 指導老師 陳炳彰 報告學生 鄭惠云 M99F0212 Sung June Chang

In the field of film quality animation, the designer usually finalizes key frame animation to make the reality, but the massive crowd animation is not possible to change every animation key because it needs huge time and memory. So the overall crowd formation is generated by computer simulation and then is divided into the small piece of scene to be easily controlled by the designer. Firstly,the divided scene is the just part of total crowd, which is not enough for the designer to view the overall crowd movement. Secondly, the key frame change in the divided scenes can cause the problems in rejoining them to make the final result because the change in the divided scene can cause side effects to the other divided scene. But it is not easy to simulate to compensate the side effect after simulating each divided scene. INTRODUCTION

Instead, our approach uses interactive LOD control to solve the cooperation of computer simulation and designer. After computer simulation, the designers can use the total crowd simulation result without dividing into scenes. The designer can control the time and memory to use the simulation result by interactively changing each LOD. If they want to view the total movement easily, then change LOD to more simple level. And they can view the detailed key frame by interactively changing LOD of the dedicated agent in the same scene. So they can retouch each agent’s key frame while viewing total agent’s movement. In this paper, the first part explains interactive LOD control, which is divided into the introduction of three different detail levels of LOD, high level software structure and block diagram style’s algorithm. And the second part shows how to use interactive LOD control in our film making pipeline. INTRODUCTION 2

Detail Level 3 kinds of detail level. - Locator level - Hexahedron level - Real model level

Fig. 1 Detail Level (Locator, Hexahedron, Real model)

Fig. 2 Software date structure

Fig. 3 Algorithm of interactive LOD

Our crowd animation pipeline consists of base work, design work, and simulation work. In base work, we collect crowd motion by motion capture and film quality texture model by various texture maps, and then make crowd formation in computer simulation work. Lastly, we finalize animation key in the result of simulation by design work to make the reality of each agent’s motion which is near the camera view because the error of motion is observed easily in close shot. Pipeline

The problem of general film quality’s crowd animation pipeline is the cooperation of computer simulation and designer’s post processing which is necessary to make film quality animation. Animation editing by designer necessarily needs to show the real look model but we cannot display many real look agents in one scene because of heavy time and memory usage of the real model. So we adapt the interactive LOD control. We select the locator and hexahedron level of detail in extra agents to show overall crowd formation change without time and memory problem, and at the same time we select the real model level in the leading agents whose animation needs to be edited by the designer. Application

In the application, we adapt real model view and hexahedron view at the same time. For default view, we use hexahedron view because it shows the volume but it is not heavy. And we change view agents in the bottom of Fig. 4 by selecting each agent and changing its view into real model view to see the real motion. So we can observe both real motion of agents and total crowd formation at the same time. And when we want to change key animation of one agent, we need to change others view into locator view because changing key needs to minimize display time which is consist of displaying other agents. Application 2

Fig. 4 Application of LOD

This paper proposes interactive LOD control for film quality crowd animation. In the field of film quality animation, the designer Firstly, we show our 3 different LOD view which consist of locator view, hexahedron view, and real model view, its 2 layer software structure which consist of management layer and realization layer, and its algorithm. Secondly, application of interactive LOD control in real film making is explained. We suggest how to change the pipeline of crowd animation in film making, and explain our application of crowd animation in film making. Conclusion

Our method successfully shows overall crowd movement and detail motion of selected character at the same time. So designers can easily finalize key frame animation in the close shot considering overall crowd. We want to improve our algorithm in many points. We plan to automate view change process. For example, view can be changed according to the distance of camera. Various kinds of LOD are also needed. And automatic converting from normal scene into interactive LOD is necessary. Conclusion

End