a method for generating flow maps using hierarchical clustering given a set of nodes, positions, & flow data between the nodes. flow maps aim to show the movement of objects from one location to another, such as the number of people in a migration, the amount of goods being traded, or the number of packets in a network.
the advantage of flow maps is that they reduce visual clutter by merging edges. most flow maps are drawn by hand & there are few computer algorithms available. this particular technique is inspired by graph layout algorithms that minimize edge crossings & distort node positions while maintaining their relative position to one another.
see also pivotgraph.