Monday, October 1, 2007

Paulson

Recognizing and Beautifying Low-level Sketch Shapes with Two New Features and Ranking Algorithm - Paulson and Hammond

Summary
Paulson has developed a new low level shape recognizer supplemented by two novel features. The first is normalized distance between direction extremes (NDDE), the distance between the point with the highest direction and the lowest direction divided by total stroke length. Next is direction change ratio (DCR), which is the maximum change in direction divided by the average change in direction. Both are used to determine the spikiness of the direction graph. Both, along with direction, curvature, and speed graphs and corners, are computed during the "pre-recognition" phase of the recognizer. Next, a series of tests determine if the sketch can be classified as one of several primitives. These are Line, Poly-line, Circle, Arc, Curve, Ellipse, Spiral, and Helix. Additionally, a stroke may be classified as a Complex figure. If classified as Complex, the stroke is subdivided into subsegments until each subsegment can be classified as under one of the low level shapes. Complex, Poly-line, and Curve classes are further distinguished by a ranking system. Each subsegment is assigned a weight associated with the complexity of the assigned shape. The weights are summed over the stroke and the interpretation with the lowest score wins. Next low level shapes are hierarchically added to an interpretation.

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