In order to solve the current situation that unmanned aerial vehicles (UAVs) ignore safety indicators and cannot guarantee safe operation when operating in low-altitude airspace, a UAV route planning method considers regional risk assessment is proposed. Firstly, airspace discretized based on rasterization, then characteristics environmental are combined quantify value obtain 3D map. The path t...

We present the rst polynomial-time algorithm that nds the shortest route in a simple polygon such that all points of the polygon are visible from the route. This route is called the shortest watchman route, and we do not assume any restrictions on the route or on the simple polygon. Our algorithm runs in worst case O(n 6) time, but it is adaptive making it run faster on polygons with simple str...

In the Internet, ISPs adopt local routing polices to choose routes to achieve objectives such as reducing cost, increasing revenue, reducing latency, and avoiding congestion. Recently, systematic models (e.g., [3]) are proposed to study the stability of path-vector, policy-based interdomain routing. Gao and Rexford [2] prove the surprising result that the constraints on local routing policies d...