A Recognizer for Free-Hand Graph Drawings

Interactive multimedia such as computer simulations and animations received increased attention over the years as supplementary teaching tools and have now become integral components of most engineering and science curriculums. We believe one way to boost the utility of such simulations and animations is to make them easier to use. In this paper, we describe a pen-based interface for constructing weighted and unweighted graphs which functions as a front-end to shortest path and minimum spanning tree (MST) algorithm simulators that we have developed. We compare the usability of this pen-based interface to that of a WIMP-based interface and a hybrid interface that uses a mixture of pen-based and WIMP-based input methods. We report evaluation results on the usability of the three types of interfaces that we have developed. Our results show that a purely pen-based approach to graph creation may actually suffer from the relatively higher misrecognition rates of the harder-to-recognize symbols and inhibit usability. We conclude that a hybrid approach which combines a soft-keyboard with graph recognition outperforms interfaces that are purely pen-based or WIMP-based.