PNNL

Abstract

We introduce an information visualization technique, known as GreenCurve, for large sparse graphs that exhibit small world properties. Our fractal-based design approach uses spatial cues to approximate the node connections and thus eliminates the links between the nodes in the visualization. The paper describes a sophisticated algorithm to order the neighboring nodes of a large sparse graph by solving the Fiedler vector of its graph Laplacian, and then fold the graph nodes into a space-filling fractal curve based on the Fiedler vector. The result is a highly compact visualization that gives a succinct overview of the graph with guaranteed visibility of every graph node. We show in the paper that the GreenCurve technology is 1) theoretically sustainable by introducing an error estimation metric to measure the fidelity of the new graph representation, 2) empirically rigorous by conducting a usability study to investigate its strengths and weaknesses against the traditional graph layout, and 3) pragmatically feasible by applying it to analyze stressed conditions of the large scale electric power grid on the west coast.