Expressive interactions - supporting collaboration in urban design

This paper discusses technological interventions in support of planners, citizens and other stakeholders in envisioning and nego-tiating an urban project. A set of prototypal tools, including a tangible user interface, has been developed that allow users to create and manipulate visual/auditory scenes and mesh these scenes with the real environment of an urban site. The paper discusses how toallsupport users - different types of stakeholders - in the collaborative creation of mixed reality configurations as an integral part of expressing their ideas about an urban project, distinguishing between different types and levels of cooperation. It also looks into how to use mixed reality tools for enhancing an already highly developed representational culture.