Gestures without Libraries, Toolkits or Training

Jacob O. Wobbrock, Andrew D. Wilson, Yang Li

Summary
The goal of this paper was to produce the $1 recognizer--a recognizer that is simple to create (less than 100 lines of code) and accurate.
The algorithm is as such:
1- Resample point path by calculating the total point path. Divide this length by the # of points (32 <= N <= 256; N = 64 seems to work well ) minus 1 to get the distance between points. Then, redraw the shape with this spacing between points.
2- Rotate the image based on the indicative angle (i.e. angle between centroid of figure and figures first point becomes horizontal--use golden section searching?)
3- Scale to a reference square and translate centroid to origin
4- Recognize the sketch by comparing it to a template (using Euclidean distance between sketch and template)

Discussion
If it is possible to create enough templates then this method seems to have some potential; however, I think that would be pretty difficult. Also, finding that angle is a pretty complicated thing to do and it doesn't allow for a robust input set as orientation is difficult to reproduce. I would like to see an animation of the system trying to find the correct angle as I think that would be instructive. Also, id they changed the location of the angle end-points then it might be easier to do the rotation.