Time difference of arrival-based localization systems successfully utilized the consensus functions, which provide robust location estimates even in extremely hostile environments, when a large number of measurements are outliers. The naive calculation of the consensus function, however, is computationally expensive, thus various acceleration methods are utilized. In this paper a special property of the consensus function is experimentally studied and validated. The property allows the construction of an upper bound of the consensus function in a spherical region in space. Based on this property a fast search algorithm is constructed, which requires an order of magnitude less computation than earlier acceleration methods.

When digital applications aim to blend virtual and real worlds, understanding the actual physical actions of users becomes an important task; the precise timing of these tangible interaction events is needed, along with the identity, and possibly location and history, of all involved actors/objects. With multiple actors or objects, it is difficult to identify who touches which object and when. Instrumenting objects for Body Channel Communication (BCC) allows message exchange around the human body between instrumented objects and the user themselves. In this paper we show how BCC can be utilized to perform under real-time conditions so that we can directly notice touch events (and the identity of actors). TangibleID is a framework that unifies tangible interaction capture for objects and users based on wearable BCC. TangibleID provides identification and communication with tagged objects/users in less than 120 ms and supports a variety of tangible interactions, without the need to restrict user (hand) movements or to maintain line-of-sight connection to cameras. When an AR application is combined with TangibleID, a new tangible mixed reality experience is achieved, as demonstrated in the “Haunted Castle” showcase. The paper presents an end-to-end technical evaluation including trade-offs regarding robustness and speed of touch recognition, outlines the breadth of interaction modalities, and reports on an initial user assessment.

Novel interactions that capacitively couple electromagnetic (EM) fields between devices and the human body are gaining more attention in the human-computer interaction community. One class of these techniques is Body Channel Communication (BCC), a method that overlays physical touch with digital information. Despite the number of published capacitive sensing and communication prototypes, there exists no guideline on how to design such hardware or what are the application limitations and possibilities. Specifically, wearable (groundless) BCC has been proven in the past to be extremely challenging to implement. Additionally, the exact behavior of the human body as an EM-field medium is still not fully understood today. Consequently, the application domain of BCC technology could not be fully explored. This paper addresses this problem. Based on a recently published general purpose wearable BCC system, we first present a thorough evaluation of the impact of various technical parameter choices and an exhaustive channel characterization of the human body as a host for BCC. Second, we discuss the implications of these results for the application design space and present guidelines for future wearable BCC systems and their applications. Third, we point out an important observation of the measurements, namely that BCC can employ the whole body as user interface (and not just hands or feet). We sketch several applications with these novel interaction modalities.