ABSTRACT
This chapter discusses techniques used to sample and acquire the sketched strokes, online sketch recognition, as well as observations on sketching habits, for example, the order with which specific shapes are drawn, which facilitates the interpretation of the sketches. It discusses the requirements of interactive sketch-based interfaces, namely the need to make the sketch-based interface as intuitive as possible, without overburdening the user with interactions which interrupt the sketching process. Throughout this discussion, reference will be made to existing, online sketch-based modeling interfaces, noting in particular, how these address the needs and requirements of such an interface. In offline interpretation, there is plenty of work focusing on 2D drawings depicting 3D shapes. However, much of the work in the online domain has been developed for 2D symbolic sketches. The largest online sketch databases are also of this nature.
