Abstract
In this paper, we present the underlying principles, implementation issues, and several running examples of Delaunay, a constraint-based data visualization system supporting a visual query language. Key components of Delaunay are its efficient constraint solver, the interface modules supporting advanced visualization, and the expressiveness and effectiveness principles it incorporates. Our successful implementation demonstrates the feasibility of a powerful visualization system that allows domain-independent and tailorable visualizations to be specified using visual programming.