Sketch based interfaces: early processing for sketch understanding

Paper
Sezgin, Tevfik Metin, Thomas Stahovich, and Randall Davis. "Sketch based interfaces: early processing for sketch understanding." ACM SIGGRAPH 2006 Courses. ACM, 2006.
Publication Link: http://dl.acm.org/citation.cfm?id=1185783

Summary

Sezgin et al. develop an intelligent sketch interface. The system allows free-form sketch input, and subsequently beautifies and identifies basic components entered. This is accomplished in 3 stages: a stroke approximation stage, a beautification stage, and a final recognition stage. The first stage uses an algorithm based on speed thresholds to identify properties of basic strokes. The second stage makes minor adjustments to formalize sketch properties (such as straightness of lines, curves etc) and enforcement of geometric properties such as perceived parallel or orthogonal relationships. While the final stage applies basic object recognition using template matching.

Discussion

Pros

The paper was very well written.
The use of motion characteristics of sketches was very interesting.

Cons.

 I wonder why they only use speed. I would think acceleration and other properties relating to movement can provide useful information as well.