$1

$1

Wobbrock et al

Does template matching starting with a single example for each class.

Step 1: Resample to 64 points
Step 2: Rotate so that the line between the starting point and the centroid (average (x,y)) is horizontal (centroid at origin)
Step 3: Scale to a reference square and translate so that the centroid becomes the origin.
Step 4: The pathwise distance between the templates and an input is computed by averageing the distance between corresponding points. This pathwise distance is determined as the minimum distance over several possible rotations of the input over +/-45 degrees. Adding additional templates with the same name can capture variations of that class. $1 performs on par with Dynamic Time Warping, and both outperform Rubine.

Discussion
The differences in error are not suprising considering some gestures are very similar from the standpoint of the features specified by Rubine, especially after rotating and rescaling. This also forces all classes to have the same value for 2 of the features, as they have the same bounding box after scaling.

Reference
Wobbrock, J., A. Wilson, and Y. Li. Gestures without Libraries,Toolkits or Training: A $1 Recognizer for User Interface Prototypes.UIST, 2007