  Route planning and navigation are common tasks that often require additional
information on points of interest. Augmented Reality (AR) enables mobile users
to utilize text labels, in order to provide a composite view associated with
additional information in a real-world environment. Nonetheless, displaying all
labels for points of interest on a mobile device will lead to unwanted overlaps
between information, and thus a context-responsive strategy to properly arrange
labels is expected. The technique should remove overlaps, show the right
level-of-detail, and maintain label coherence. This is necessary as the viewing
angle in an AR system may change rapidly due to users' behaviors. Coherence
plays an essential role in retaining user experience and knowledge, as well as
avoiding motion sickness. In this paper, we develop an approach that
systematically manages label visibility and levels-of-detail, as well as
eliminates unexpected incoherent movement. We introduce three label management
strategies, including (1) occlusion management, (2) level-of-detail management,
and (3) coherence management by balancing the usage of the mobile phone screen.
A greedy approach is developed for fast occlusion handling in AR. A
level-of-detail scheme is adopted to arrange various types of labels. A 3D
scene manipulation is then built to simultaneously suppress the incoherent
behaviors induced by viewing angle changes. Finally, we present the feasibility
and applicability of our approach through one synthetic and two real-world
scenarios, followed by a qualitative user study.
