Reference 

S. S. Intille, C. Kukla, B. Stigge, and L. Bonanni, "Merging the physical and digital in ubiquitous computing environments," Massachusetts Institute of Technology, Cambridge, MA, MIT Dept. of Architecture House_n Project Technical Report, 2001.
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Abstract 

Designing digital interfaces for physical environments with ubiquitous displays and sensing introduces a new set of human-computer interaction challenges. Physical objects, digital interfaces, and multi-person human activity must be simultaneously considered. We are building and testing physical components for an interactive environment that merges the physical space and the digital interface. We have identified three types of expectations of constraints that users bring to the new environment: architecturalconstraints, device-level constraints, and widget-level constraints. 

Keywords 

Ubiquitous computing, interactive environments, architecture.