Reading #1: Gesture Recognition (Hammond)

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Danielle

Summary

This article serves as a brief yet meaningful introduction to the gesture recognition systems. It mainly focuses on gestures as the one made by a pen in a 2D surface, i.e. a set of strokes. Each stroke defined as the path from the moment the pen touches the surface until it raises from it. Gesture recognition is proven to be a useful technique in some cases. However, the author does not encourage its use as main form of sketch recognition. The article also covers 3 techniques for gesture recognition. A relatively simple yet very recognized technique is the Rubine’s technique. Based on a finite set of quantifiable features of a stroke, this technique is able to determine the shape drawn taking into account that some training must occur previous to identification. An improvement of this method is proposed by Long, mostly by modifying the feature set, however many think that the improvement is not significant enough to pay the overhead of calculating a bigger feature set. Another very different approach is presented by Wobbrock, who proposes a simpler algorithm to implement, which also appears to have better accuracy than Rubines, however some of its drawbacks are that the running time to detect a shape is much longer than Rubine’s and also it omits information of the stroke that can be important in some cases (e.g. direction of a line).  In general this article introduced gesture recognition as a way of recognizing shapes in a 2D surface, and presented 3 methods to achieve it. It was emphasized that gesture recognition depends on the way a shape is drawn (path of the pen), instead of focusing on the shape itself.

Discussion

This reading presents a good, easy to read introduction to gesture recognition, which I think is an efficient and useful technique for many cases where the user can be trained or is able to provide enough training to the recognizer. Rubine proposed a method that is still very used, which does not mean that is the best method one can imagine, but proves that it is adequate enough for most practical cases. The $1 dollar method on the other hand comes with high accuracy and simplicity in implementation but perhaps a high price to pay which is the running time. In many gesture recognition systems it is often wanted that the shape is not only recognized correctly but also quickly. A nice example of this is a Palm device, where a long recognition time could really ruin the whole user experience since every word would take too long to be written. In general I found first reading very handy as it not only describes gesture recognition in a simple and complete way but also gives an important first glimpse of the sketch recognition world.