Visualisation and Analysis of Directed Graphs in 3D (Hong/Nikolov)
This is an example of a network of the e-mail communication in an office over a four month period. Each node represents a person and each edge represents at least one e-mail exchanged between two people. The color of the nodes is related to their degree centrality.
The 3D drawing convention that we study consists of splitting the graph into too parts and drawing each of them as a 2D hierarchy in a plane. The two planes are parallel. We can make the hierarchy easier to comprehend by imposing direction on the edges from the node with a higher degree centrality to the node with a lower degree centrality. The color of the nodes is loosely related to their position in the hierarchy.
We can combine the visual representation of the degree centrality with a visual representation of the eigenvector centrality by the size of the nodes.
Alternatively, we can split the hierarchy in more than two parallel planes placing each node at the barycenter of its neighbors on the level below it.
These methods are implemented as a part of GEOMI, a visual analytic tool being developed by the VALACON project.