This paper describes a path planning method for
a small autonomous aerial vehicle to be used for inspecting
overhead electricity power lines. A computational algorithm is described which
converts a standard three dimensional array representation of one or
more obstacles in the vehicle's environment into an octree and
a connectivity graph. This achieves a significant reduction in computer
memory usage and an increase in execution speed when the
graph is searched. Path planning is based on a three-dimensional
extension of the distance transform. Test results demonstrate rapid and
effective operation of the planner within different workspaces.