Reading 8: Specifying Gestures by Example

Citation

Rubine, Dean. Specifying gestures by example. Vol. 25. No. 4. ACM, 1991.

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Summary

Rubine has 13 features which can be used to classify sketches. The 13 features are as follows:

1) Cosine of starting angle

2) Sine of starting angle

3) Length of bounding box diagonal

4) Angle of bounding box diagonal

5) Length of start to end point

6) Cosine of angle from start to end point

7) Sine of angle from start to end point

8) Stroke length

9) Total relative rotation

10) Total absolute rotation

11) Total squared rotation (sharpness)

12) Maximum speed

13) Total time

Discussion

A linear classifier is also specified in which each new class is trained by creating a new linear function. When doing classification, the function value is calculated for all possible classes and the class with the maximum function value is chosen as the selected class. This provides a very easy and efficient way to classify sketches but might be influenced hugely by a bad initial training example, thereby degrading the accuracy of classification step later.