Analyzing sketch content using in-air packet information.

ABSTRACTRecognizing hand drawn mathematical matrices on tablet computers has proven to be a particularly challenging task. While individual expression recognition can be simplified by assuming the entire content is a single semantic construct, a single math expression, a matrix is composed of multiple expressions arranged in rows and columns. These expressions must first be segmented into matrix elements, and then each individual matrix element expression must be recognized. In this work, we show how a simple algorithm on in-air (i.e. non-inking) strokes can be used to analyze the drawing order of a matrix. Once the drawing order is recognized, we show how outlier analysis on in-air packets gives rapid, reliable segmentation of matrix elements.