SketchNode: Intelligent sketching support and formal diagramming. The primary motivation for building SketchNode is to provide an environment for exploring how people use tools to create, arrange, edit and interpret graph diagrams. It has two equivalent interfaces: sketching and diagramming, so that the functional requirements and advantages and disadvantages of the differences can be studied. In this paper we describe two iterations of SketchNode, in particular the computational intelligence required to maintain a sketch that appears hand-drawn and the complexity of providing two interfaces that are equivalent in terms of interaction and visualization. The development and usability tests presented here contribute to the understanding of what intelligent sketch diagramming tools can support and the interaction paradigm of dual visualization tools.