parameters are to be considered for path planning of an UAV: certain distances like UAV system to target position (if target is known prior), UAV to nearest obstacle distance and time taken by the UAV system to reach its destination.
generally these three parameters are considering for trajectory planning. But, in the case of UAV u should be aware of its dynamics.
weight,shape and body dimensions,length the blades,wings extend,range at which moves,speed, location of sensors, obstacle distance,shape and movement details(if moving,even its velocity), planning algorithm,even the kind of control system in the uav is responsible.