One of the recent design goals in human computer interaction (HCI) has been to extend the sensory -motor capabilities of computer systems to combine the real and the virtual in order to assist the user in his environment. Such systems are called augmented reality (AR). This is also the objective of other innovative interaction paradigms such as ubiquitous computing, tangible bits, pervasive computing and traversable interfaces .
Augmented reality (AR) has been the subject of growing interest. In [Dubois 99], we emphasised the diversity of AR systems and presented one important classification characteristic:
Systems that enhance interaction between the user and her/his real environment by providing additional capabilities and/or information. We call such systems augmented reality (AR) ones.
Systems that make use of real objects to enhance the interaction between a user and a computer. We call such systems, augmented virtuality (AV) ones.
There are many application domains of augmented reality (AR) and augmented virtuality (AV), including construction, architecture and surgery [Dubois 99]. Examples of AR systems are the computer assisted medical intervention (CAMI) systems, also called augmented surgery . AR plays a central role in the medical domain because the key point of CAMI systems is to "augment" the physical world of the surgeon (the operating theatre, the patient, the tools etc.), by providing pre- operative information including the pre-planned strategy. Information is transmitted between the real world and the computer world using different means: computer screens, mouse, pedals, tracking mechanisms, robots, etc. Examples of AV systems in human-computer interaction involve input modalities based on real objects (cubes), such as the phicons ( physical icons ) [Ullmer 98]. Ishii has described this interaction paradigm as the tangible user interface . All these systems are all based on the manipulation of objects in the physical environment.
AR and AV systems are numerous in many different application domains but the most attention has been paid to the technical issues related to image processing and data fusion. Very little effort has been applied to modelling the interaction between the user and the system. The design approach so far has been technology-driven. In our project, we adopt a complementary user-centred approach providing a usercentred design method based on scenarios. Our application domain is archaeological prospecting.
In this chapter, we first present the main characteristics of archaeological prospecting. Indeed we base our study on a specific mobile fieldwork : archaeological prospecting We then explain our design approach for mobile AR systems based on field studies and on the design of scenarios of actual and expected activities. We then describe the conceived and developed interaction techniques via the MAGIC ( mobile augmented reality group in context ) platform.