Using scribble gestures to enhance editing behaviors of sketch recognition systems
Wenzhe Li, Tracy Hammond · 2012
Mechanix is a computer-assisted tutoring system for engineering students. It uses recognition of freehand sketches to provide instant, detailed, and formative feedback as a student progresses through each homework problem. By using recognition algorithms, the system allows students to solve free-body diagrams and truss problems as if they were using a pen and paper. However, the system currently provides little support for students to edit their drawings by using free hand sketches. Specifically, students may wish to delete part or the whole of a line or shape, and the natural response is to scribble that part of shape out. We developed a new method for integrating scribble gestures into a sketch recognition system. The algorithm automatically identifies and distinguishes scribble gestures from regular drawing input using three features. If the stroke is classified as a scribble, then the algorithm further decides which shape or which part of shape to be deleted. Instead of using slower brute-force methods, we use geometric-based linear-time algorithms which efficiently detect a scribble gesture and remove the intended shapes in real-time.