$N-protractor: a fast and accurate multistroke recognizer

  • Authors:
  • Lisa Anthony;Jacob O. Wobbrock

  • Affiliations:
  • University of Maryland, Baltimore County;University of Washington

  • Venue:
  • Proceedings of Graphics Interface 2012
  • Year:
  • 2012

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Abstract

Prior work introduced $N, a simple multistroke gesture recognizer based on template matching, intended to be easy to port to new platforms for rapid prototyping, and derived from the unistroke $1 recognizer. $N uses an iterative search method to find the optimal angular alignment between two gesture templates, like $1 before it. Since then, Protractor has been introduced, a unistroke pen and finger gesture recognition algorithm also based on template-matching and $1, but using a closed-form template-matching method instead of an iterative search method, considerably improving recognition speed over $1. This paper presents work to streamline $N with Protractor by using Protractor's closed-form matching approach, and demonstrates that similar speed benefits occur for multistroke gestures from datasets from multiple domains. We find that the Protractor enhancements are over 91% faster than the original $N, and negligibly less accurate (e.g., pen vs. finger) have on recognition accuracy, and examine the most confusable gestures.