POS Polyline Smoothing: Reduction of Polyline Vertices

摘要

The POS polyline smoothing algorithm was developed to reduce the needed storage and rendering complexity of polylines by the removal of vertices with two goals in mind. First was to define a single algorithm that would produce a 'good enough' result with varying characteristics, which are user defined. The concept of 'good enough' is built on the trade of time vs. precision, where the best result takes the longest time and the quickest maybe less than desirable form. The second goal was to incorporate surrounding data into the set of control factors. To accomplish this, the concept of Points of Significance (POS) was developed. POS can be a group of individual points, or the point that represents more complex shapes or regions. The complete Set of POS is divided into subsets by the polyline, and by maintaining these subsets the algorithm insures that the polyline maintains a proper relationship with the surrounding data. It is the use of POS that makes this algorithm so powerful. The smoothing is complete after a maximum number of successive passes are made through the polyline, or no additional removals can be made without violating the control factors.