  This paper describes a fast approach to automatic point label de-confliction
on interactive maps. The general Map Labeling problem is NP-hard and has been
the subject of much study for decades. Computerized maps have introduced
interactive zooming and panning, which has intensified the problem. Providing
dynamic labels for such maps typically requires a time-consuming pre-processing
phase. In the realm of visual analytics, however, the labeling of interactive
maps is further complicated by the use of massive datasets laid out in
arbitrary configurations, thus rendering reliance on a pre-processing phase
untenable. This paper offers a method for labeling point-features on dynamic
maps in real time without pre-processing. The algorithm presented is efficient,
scalable, and exceptionally fast; it can label interactive charts and diagrams
at speeds of multiple frames per second on maps with tens of thousands of
nodes. To accomplish this, the algorithm employs a novel geometric
de-confliction approach, the 'trellis strategy,' along with a unique label
candidate cost analysis to determine the "least expensive" label configuration.
The speed and scalability of this approach make it well-suited for visual
analytic applications.
