Segmentation of Pen Strokes Using Pen Speed

We present a technique for segmenting pen strokes into lines and arcs. The technique uses pen speed information to help infer the segmentation intended by the drawer. To begin, a set of candidate segment points is identified. This set includes speed minima below a threshold computed from the average pen speed. It also includes curvature maxima at which the pen speed is again below a threshold. The ink between each pair of consecutive segment points is then classified as either a line or arc, depending on which fits best. Finally, a feedback process is employed, and segments are judiciously merged and split as necessary to improve the quality of the segmentation. Formal user studies were conducted, and our system was observed to perform accurately, even for new users.