Sketch Based Interfaces: Early Processing for Sketch Understanding

Tevfik Metin Sezgin, Thomas Stahovich, and Randall Davis. 2006. Sketch based interfaces: early processing for sketch understanding. In ACM SIGGRAPH 2006 Courses (SIGGRAPH '06). ACM, New York, NY, USA, , Article 22 . DOI=10.1145/1185657.1185783 http://doi.acm.org/10.1145/1185657.1185783


This paper describes a sketch interface which uses multiple sources of knowledge to provide processing of freehand sketches. The approach consists of three phases: approximation, beautification, and basic recognition. The paper spends most of its time describing approximation. Approximation uses data from stroke direction and stroke speed. An interesting aspect of the work is the hybrid fit technique, which generates a set of potential fits and selects the best one. A practical approach to handling discretization of bezier curves is also provided for handling curves. Beautification is briefly discussed as adjusting the slopes of lines using a clustering method. Basic recognition is carried out using a set of hand tailored templates. An evaluation was conducted in which 13 of 14 students liked this system better than a non-sketch alternative tool. The system displayed 96% accuracy.


This work has definite application domains, but the state of the system described in this paper seems unprepared for general usage. Specifically, the hand-tailored recognition templates seem a bit terrifying, but perhaps in a restricted domain that isn't an issue. The user study conducted for this system was very informal and probably shouldn't have been reported in this paper. My final complaint is about beautification. I don't like it in some cases, and I think depending on the software, the interface must support a more interactive experience using the pen, rather than just converting what I sketch into primitives.