Proportional Contact Representation of Planar Graphs

Stephen Kobourov

Abstract

In a proportional contact representation of a planar graph, each vertex is represented by a simple polygon with area proportional to a given weight, and edges are represented by adjacencies between the corresponding pairs of polygons. We show how to use Schnyder realizers and canonical orders for planar graphs to obtain different types of contact representations. Specifically, we describe an algorithm that guarantees 10-sided rectilinear polygons and runs in linear time. We also describe a construction with 8-sided polygons, which is optimal in terms of polygonal complexity as 8-sided polygons are sometimes necessary. Specifically, we show how to compute the combinatorial structure and how to refine it into an area-universal rectangular layout in linear time. However, to compute the exact representation from the area-universal layout required numerical iteration, or can be approximated with a hill-climbing heuristic.