Building wide-area applications with the ARToolkit

We show how splitting the ARToolkit in several functional components leads to an extension of its capabilities. We present how these ARToolkit 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 ARToolkit 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 ARToolkit provides all features necessary for this application, 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 ARToolkit 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.