In this paper we propose solutions that allow several co-located city planners to perform domain-specific interaction tasks together in one semi-immersive pro jection-based VR system. After a registration process, e.g., by posing gestures or by using speech commands, this group activity can be performed either in a cooperative mode, i.e., tasks are accomplished consecutively, or in a col laborative interaction mode, i.e., users collaborate simultaneously.
Both modes as well as multimodal concepts for the registration process are discussed and evaluated. Further VR-based interaction strategies for the city planning domain are presented, which are adapted to the demands of city planners working together in a shared virtual environment.

@inproceedings{SRH06,
  author = {Steinicke, Frank and Ropinski, Timo and Hinrichs, Klaus H.},
  title = {Collaborative Interaction Concepts for City Planning Tasks in Projection-Based Virtual Reality Systems},
  booktitle = {Proceedings of Virtual Reality International Conference (VRIC)},
  pages = {113--122},
  year = {2006},
  publisher = {IEEE Press},
  address = {Laval},
  keywords = {3dsp, vr},
  url = {http://viscg.uni-muenster.de/publications/2006/SRH06},
}