Edge Routing and Bundling for Graphs with Fixed Node Positions

In some graph drawing scenarios, the positions of the nodes are already defined and cannot be modified (for example, they were provided by the user) and the graph drawing techniques are only used to draw edges between the nodes. The number of nodes in such cases tends to be relatively small (tens or hundreds of nodes at most) however the users want to see all of the edges. Various edge routing techniques can provide such services, but if the graph is dense, the drawing can get rather hard to read due to the high number of lines required to visualize the edges. In such cases, clarity can be improved by bundling individual edges (more precisely parts of their drawing) into larger groups and draw as a single line. In this paper, we provide several different techniques for edge bundling based on an edge routing algorithm, compare and evaluate them.