Another approach to this is to bring the interaction into the hands of the user. These take the idea of adding displays to the real world to an even more integrated level. Combining augmented reality and augmented virtuality yields what we call dual augmentation. An understanding of dual augmentation benefits from a conceptual model of the connections between the real space and its virtual model. The canonical MUD is an object-oriented database which contains objects representing things, people, and spaces and uses a coherent metaphor which maps nicely onto a physical space.
Information sensed in the physical world is used to update information in the virtual world.
Information from the virtual world is used to produce some affect in the physical world. These can be used to access parts of the virtual world which have no real-world counterpart. For example, our extended refrigerator, CyberFridge, has a GUI display attached to its freezer door. This display lets the user see virtual information such as posted notes that have no physical instantiation. It also gives them access to a recipe program and other virtual services.