Dynamic label placement for moving objects

Sammanfattning: In command and control systems, for example air traffic control, operators must view many moving objects simultaneously. Graphical labels that identify objects move along with them, and for readability it is important that such labels do not overlap or hop around erratically as objects come close to each other. Instead, the labels should smoothly revolve around their objects. The goal of this thesis is to explore label placement strategies for moving objects that avoid overlap and hopping effects. In this thesis, we consider a simplified problem, in which time is coarsely discretized and each label is of a fixed size and can only be displayed in a limited number of distinct positions relative to its corresponding object. An optimal and a reactive heuristic algorithm are developed and applied to a number of test cases, which are then analysed for different statistical measures. In a scene with 25 objects traveling across a common area, the reactive algorithm is on average able to keep approximately half of the labels visible the whole time, whereas the optimal algorithm could only be applied to test cases with at most four objects. A prediction mechanism is implemented that on average decreases the number of times labels alternate between being hidden and visible. Future work could investigate how users perceive the usability of a system implementing the reactive algorithm.