> Does he go into N layer PCBs, or is this constricted to just two layer?
The thesis describes routing of multi layer boards. Long traces are split into subparts, which than are designed to different layers by a greedy opimizeation algorithm, and the shorter traces are than rubberband routed and connected by vias. For the colors in the pictures: The colored traces are the result of the dijkstra shortest path algorithm, which follows the edges of the delaunay triangulation. That dijkstra routing is then collapsed like rubberbands to the black curved traces, which are then finally the real copper traces on the PCB board. Dijkstra routing and rubberband creation is by far the most daunting task, and unfortunately not described in much detail in his thesis. The layer assignment is described well and is easy to implement. The dijkstra routing is of course much more advanced as the plain pathfinding which one learns at university. One has to remember if the path makes left or right turns and other conditions. Rubberband collapsing is also not that easy. The terminals are described as disks in 2d, and concave traces relax on the convex hull on the disks. And finally the rubberbands, when they are relaxed and attached to the disks, have to be sorted, which took me some time to get it right. Another important point is the region split: Whenever one more trace is routed, that trace divides the whole set of terminals in two halves, as a routed trace can never be crossed by later routed traces. Reading the thesis is indeed some fun.
