Reading 25: Who dotted that 'i'?: context free user differentiation through pressure and tilt pen data

Citation

Eoff, Brian David, and Tracy Hammond. "Who dotted that'i'?: context free user differentiation through pressure and tilt pen data." Proceedings of Graphics Interface 2009. Canadian Information Processing Society, 2009.

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Summary

The paper presents a novel way to distinguishing who is using the pen on a sketch input surface by using features based on pen tilt, pressure and speed. The paper presents two experiments: 

1) First experiment proves that tilt, pressure and speed features are consistent for a user within a certain sketch and also consistent in time varying in hours or days. 

2) The second experiment tries to match a given set of tilt, pressure and speed features to a unique user. The paper uses k nearest neighbor classifier and gets an accuracy of 97.5 percent to distinguish two users and an accuracy of 83.5 percent to distinguish ten users simultaneously.

Discussion

The paper presents 24 features based on pen tilt, pressure and speed. 14 are based on pen tilt, 7 based on pressure and 3 based on speed. The features used in the paper are as follows:

The authors found out as the set size of the number of users to distinguish increases, the accuracy decreases.