Reading #9 PaleoSketch: Accurate Primitive Sketch Recognition

Reading #9 PaleoSketch: Accurate Primitive Sketch Recognition

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Yue Li

Summary:

PaleoSketch is a low-level (primitive) recognizer, which can deal with 8 basic shapes (line, polyline, circle, ellipse, arc, curve, spiral and Helix) with recognition more than 98%. In addition, it doesn’t ask users to always draw in certain way and leave them more freedom.

This recognizer first use pre-recognition to do some preparation for future shape test. It includes removing consecutive, generating some graphs and values, computing NDDE and DCR (which are useful for distinguishing polyline and arcs) and removing tails. In addition, the stroke is also tested for whether being over traced and closed.

Then, PaleoSketch conducting test for each basic shape. These tests are based on the feature of the shapes and some manually defined thresholds. A complex test is also used to deal with strokes that are better defined as the combination of more than 1 primitive.  The recognizer use a ranking algorithm to order all the interpretation and choose the best fit from them.

Discussion:

PaleoSketch analysis the characteristic of each shape and computing some useful features to evaluate them, and its results are important for high-level recognizers. For each stroke, it uses all the tests and then finds the best fit from them. This could be time consuming. If the test itself can generate an absolute confidence of being this kind of shape, maybe we can avoid doing other tests anymore.