We propose local mechanisms for efficiently marking the
broader network region around obstacles, for data propagation
to early enough avoid them towards near-optimal
routing paths. In particular, our methods perform an online
identification of sensors lying near obstacle boundaries,
which then appropriately emit beacon messages in the network
towards establishing efficient obstacle avoidance paths.
We provide a variety of beacon dissemination schemes that
satisfy different trade-offs between protocol overhead and
performance. Compared to greedy, face routing and trustbased
methods in the state of the art, our methods achieve
significantly shorter propagation paths, while introducing
much lower overhead and converging faster to near-optimality.