Arno Kamphuis

Finding paths for coherent groups using clearance

Virtual environment are often populated with moving units and the paths for these units should be planned. When multiple units need to exhibit coherent behavior in a cluttered environment, current techniques often fail, i.e. the resulting paths for the units in the group lack the coherence required. In this paper, we propose a novel approach to motion planning for coherent groups of units. The method presented uses a path for a single unit, called the backbone path, which can be generated by any motion planner. This backbone path is extended to a corridor using the clearance along the path. The units can move freely inside this corridor. By limiting the width of this corridor, and the extent along the corridor where the units can move to, the approach guarantees coherence of the group. Experiments show that the generated paths exhibit group coherence as required, like passing on the same side of obstacles and waiting for fellow group mates to catch up. Performance measurements show that the approach is capable of generating the paths in real-time. In our implementation, the method requires just a few percent of the processor time for groups consisting of up to 100 units.

High quality navigation in computer games

Navigation plays an important role in many modern computer games. Currently the motion of entities is often planned using a combination of scripting, grid-search methods, local reactive methods and flocking. In this paper we describe a novel approach, based on a technique originating from robotics, that computes a roadmap of smooth, collision-free navigation paths. Because the vast amount of computation time is spent in the pre-processing phase, navigation during the execution of an application is almost instantaneous. The created roadmap can be queried to obtain high quality paths. Furthermore, the applications of the roadmap are not limited to navigating an entity. Therefore, besides navigation for an entity, two other applications are presented; one for planning the motion of groups of entities and one for creating smooth camera movements through an environment. All applications are based on the same underlying techniques.

Motion planning for coherent groups of entities

Motion planning for multiple entities is a challenging problem in todays virtual environments. In this paper we develop an innovative approach to motion planning for groups of entities, where coherence is taken into account. We model the group by a deformable shape. Next, we use the Probabilistic Roadmap Method to plan the (global) motion of the shape. For this, we, develop new sampling techniques and local planners. A new approach, called Group Potential Fields, is also introduced as a means to determine the local motions of the entities inside the deformable shape. Global and local motions are then combined to find the required paths for the entities. Experiments show that the approach is able to find paths for groups of varying sizes, after limited preprocessing time, where the groups stay coherent.

Using the Corridor Map Method for Path Planning for a Large Number of Characters

A central problem in games is planning high-quality paths for characters avoiding obstacles in the environment. Current games require a path planner that is fast (to ensure real-time interaction) and flexible (to avoid local hazards). In addition, a path needs to be natural, meaning that the path is smooth, short, keeps some clearance to obstacles, avoids other characters, etcetera . Game worlds are normally populated with a large number of characters. In this paper we show how the recently introduced Corridor Map Method can be extended and used to efficiently compute smooth motions for these characters. We will consider crowds in which the characters wander around, characters have goals, and characters behave as a coherent group. The approach is very fast. Even in environments with 5000 characters it uses only 40% of the processing power of a single core of a cpu . Also the resulting paths are indeed natural.