Actually, I got the idea for the TimeRadarTrees work in my 2006 vacancies in Kerkira, Greece. Once again, I saw one of these node-link diagrams that look like a plate of Spaghetti. The diagram was extremely full of clutter that it was not useful anymore.
I asked myself if it is not possible to design a graph diagram that can visually represent a graph structure without any link crossing. I came up with the TimeRadarTrees visualization - a radial diagram that uses color coded circle sectors all differently oriented to represent the edges of a graph.
Soon, I found out that it is easily possible to extend the visual metaphor for dynamic graphs, i.e., those that change over time. Furthermore, weighted edges can easily be represented by color coded sectors and an additional hierarchy can be laid on top of the TimeRadarTrees by using a radial tree node-link diagram.
Some years later, I extended the idea of the TimeRadarTrees to the Layered TimeRadarTrees approach that generates a more scalable version of the original idea.