The above reasons made the luminous digital worlds displayed in CAVEs (Cave Automatic Virtual Environments) and Head Mounted Displays lose their appeal and that is why during the 90s there was a growing interest in techniques for combining real with virtual environments to create “Mixed Realities” – spatial environments where the participant can interact with physical and digital information in an integrated way [Milgram, 1994].
A whole new family of terms came into play, such as Augmented Reality and Tangible Bits. Augmented Reality involves overlaying and registering digital information (e.g. text and graphics) onto a real world scene in such a way that the digital information appears to be attached to physical objects, even as they move about. The physical scene might be the local environment, with the digital information being introduced via a see-through head mounted display. Alternatively, it might be remote, being viewed on a video display that is then enhanced with digital information. The approach of Tangible Bits [Ishii, 1997] involves the use of graspable physical objects called phicons2 interacting with digital information, for example moving physical models across a table top in order to access a digital map that is projected onto it.
A number of claims have been made about the benefits of these different kinds of Mixed Realities including enriching the user experience, enhancing learning and improving collaborative working and planning. However one main thesis that has been proposed is that manipulating familiar physical artefacts (e.g. toy bricks) or acting in physical spaces, when interacting with digital information, provides greater embodiment for the user compared with interacting with more abstract representations [Dourish, 2001]. In other words the kinds of interactions experienced in Mixed Reality environments fit more
The word phicon is a portmanteau based on physical and icon.
Using Everyday Objects as Communication tools
Fig. 5 See through head mounted display. [source:http://www.columbia.edu/cu/gsapp/BT RESEARCH/VR-CONST/vr-gear.jpg]
Fig. 6 ARTHUR, An Augmented Reality Application. [source:http://idwonline.de/pages/de/newsimag e16073.jpg]
Fig. 7 A Tangible Bits Application with the use of phicons [source: http://tangible.media . mit.edu/projects/tangibleviewpoints/]