Bridge Over Troubled Water

We all have our fetishes. Mine are about maps with nice curvy arrows, that's why I've spent the last two weeks at working on a nice representation of destination arrows for the units, and now I can share a couple of screenshot.
I must set up a small control about unit sizing, to let the user adjust quickly the sizes for all his waypoints, and then I can say that this part is closed.
I have now to decide what to tackle, I started thinking about calculating reinforcements. Having a continuous map I must constrain the calculation to simpler terms.