Designing a Marker Set for Vertical Tangible User Interfaces

Tangible User Interfaces (TUI)s extend the domain of reality-based human-computer interaction by providing users the ability to manipulate digital data using physical objects which embody representational significance. Whilst various advancements have been registered over the past years through the development and availability of TUI toolkits, these have mostly converged towards the deployment of tabletop TUI architectures. In this context, markers used in current toolkits can only be placed underneath the tangible objects to provide recognition. Albeit being effective in various literature studies, the limitations and challenges of deploying tabletop architectures have significantly hindered the proliferation of TUI technology due to the limited audience reach such systems can provide. Furthermore, available marker sets restrict the placement and use of tangible objects since if placed on top of the tangible object, the marker will interfere with the shape and texture of the object limiting the effect the TUI has on the end-user. To this end, this paper proposes the design and development of an innovative tangible marker set specifically designed towards the development of vertical TUIs. The proposed marker set design was optimized through a genetic algorithms to ensure robustness in scale invariance, the capability of being successfully detected with distances of up to 3.5 meters and a true occlusion resistance of up to 25%, where the marker is recognized and not tracked. Open-source versions of the marker set are provided through research license on www.geoffslab.com/tangiboard_marker_set.