# Visibility Problem - Connect all the vertices that can "see" each other - Use Dijkstra's algorithm to navigate - Points sorted in polar coordinate system - What about objects with actual volume? -- We can enlarge the obstacles and still treat the object as a point. - [[divide-and-conquer|Divide and conquer]] - Divide the line segments into two sets - Use [[sweeping|sweep line]] to calculate visibility, so that the segments are sorted from left to right.