Improved Circular Layouts

Abstract

Abstract. Circular graph layout is a drawing scheme where all nodes are placed on the perimeter of a circle. An inherent issue with circular layouts is that the rigid restriction on node placement often gives rise to long edges and an overall dense drawing. We suggest here three independent, complementary techniques for lowering the density and improving the readability of circular layouts. First, a new algorithm is given for placing the nodes on the circle such that edge lengths are reduced. Second, we enhance the circular drawing style by allowing some of the edges to be routed around the exterior of the circle. This is accomplished with an algorithm for optimally selecting such a set of externally routed edges. The third technique reduces density by coupling groups of edges as bundled splines that share part of their route. Together, these techniques are able to reduce clutter, density and crossings compared with existing methods.

Skeleton-Based Edge Bundling for Graph Visualization

“…Holten pioneered edge bundling under this name for compound (hierarchy-and-association) graphs by routing edges along the hierarchy layout using B-splines [14]. Gansner and Koren bundle edges in a circular node layout similar to [14] using area optimization metrics [13]. Dwyer et al use curved edges in force-directed layouts to minimize crossings, which implicitly creates bundle-like shapes [10].…”

StreamEB: Stream Edge Bundling.

“…Edge bundling becomes popular in Graph Drawing and Information Visualization communities to reduce visual clutter for high-level edge patterns [13,[18][19][20][20][21][22]. Most edge bundling methods, however, have focused on static graphs.…”

TGI-EB: A New Framework for Edge Bundling Integrating Topology, Geometry and Importance

“…Gansner et al [11] improved circular layouts by merging splines of edges to minimise the total amount of ink needed to draw the edges. Cornelissen et al [7] presented a circular bundle view of the hierarchical graphs to study in software engineering, such as, the program execution traces.…”

“…Recently, edge bundling methods became popular for visualising large dense networks, and have received much attention by the Graph Drawing community and Information Visualisation community [8,11,[13][14][15]. Most of the methods are based on geometry, i.e., a given drawing of graphs, to define geometry compatibility between the edges (i.e., edges are typically polylines or splines that are bundled together if they are compatible).…”