Reading 10: Visual Similarity of Pen Gestures

Citation

Long Jr, A. Chris, et al. "Visual similarity of pen gestures." Proceedings of the SIGCHI conference on Human Factors in Computing Systems. ACM, 2000.

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Summary

Long introduced used important features from Rubine and introduced 11 more features that enhanced recognition of single stroke freehand gestures. The last two features from Rubine's paper Maximum Speed and Total time were neglected because they were mostly independent from the shape of the gestures and were more dependent on the user who is drawing the sketch. The 11 new features introduced by Long are:

1) Aspect
2) Curviness
3) Total angle traversed / Total length
4) Density Metric 1
5) Density Metric 2
6) Non-subjective Openness
7) Area of bounding box
8) Log(Area)
9) Total Angle / Total Absolute Angle
10) Log(Total Length)
11) Log(Aspect)

Discussion

Many of the features used in Long's paper are log of quantities. For example Log of area is taken because it reduces the dramatic nature in difference in areas when the objects are small. The Log converts these dramatic scale into a much less extreme scale and is much more effective for the purpose of recognition.