M. Wagner Building Wide-Area Applications with the AR Toolkit The First IEEE International Augmented Reality Toolkit Workshop, Darmstadt, Germany, Sept. 29 2002. (bib)
	We show how splitting the AR Toolkit in several functional components leads to an extension of its capabilities. We present how these AR Toolkit components can be used to extend the functionality of the Toolkit to wide area indoor tracking. The marker detection gets reconfigured whenever the system's user comes near so-called transitional markers, resulting in the possibility of integrating several AR Toolkit based applications within a single system. The cost of a wide area tracking infrastructure based on optical marker detection is very low, as only some markers have to be printed out and attached to known places. The AR Toolkit provides all features necessary for this applications, but has a limited number of markers that can be stored in and distinguished by the system at a given point in time. Wide area tracking usually requires many known features in the environment. Splitting the AR Toolkit library in several components (image acquisition, marker detection and processing of the marker information) allows the realization of this wide area tracking scenario. Every component gets implemented in a separate process, communicating with each other using the DWARF system. As a result, the output of every component can be used by several others. To solve the problem of a limited number of markers we attach transitional markers at prominent places like entrance doors to buildings. Once the system detects such a marker, it loads a set of normal markers. In addition, a new set of transitional markers is loaded. Whenever the system detects one of these, it unloads the current set of markers and switches to a new set of markers. This feature allows to create an "AR Toolkit enabled building", where every room contains a distinct AR Toolkit based application. The doors of these rooms carry huge transitional markers, allowing the system to perform coarse tracking and switch to adequate high-precision tracking applications. Using the concept of transitional markers in combination with an encapsulation of AR Toolkit functionality in various components will allow a more seamless integration of wide and narrow area tracking within a single application.
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