In this paper, we proposed a new visualization framework called Marching Graph that integrates the graph metaphor and the spatial metaphor into a single visualization. Marching Graph allows users to navigate the spatially referenced relational data across two different visual metaphors. We use a force-directed layout algorithm to draw a sequence of progressive graphs, G1, G 2, ... Gn in a 2D geometric space that present the spatially referenced relational data. Each graph Gi is associated with a particular geographic region Ri presented by the spatial metaphor. We allow the user to "march" through the thematic map by altering the focus region Ri and the display of its corresponding graph Gi → Ri. The use of 2D visual metaphors facilitates the navigation activities and human cognition process significantly
