“…These proposed solutions, among many others, are dedicated for urban environments where it is assumed the surface consists only of the base plane and quadrangular prisms lying on the base plane (i.e the target moves in planar path between buildings), and all UAVs fly at some altitude over the buildings which makes them free from natural obstacles. In addition, as the agents are so far from the target and the terrain, these facts make the targets always under the camera sight, i.e the relative speed between the target and the UAV's eyes is low, for which, in most cases the target can be even considered as static, the same points are noticed for [10] where the author did not even need to consider the occlusion and the collision avoidance, meanwhile our issue compels the UAVs to be very close to the target (5-20 m) to monitor a target moving on natural no-planar surface (mountainous surface), this fact increases mainly the probability of occlusion of the line of sight, and the collision with the mountainous surface, which push us to exclude these solutions adapted for the usual surveillance tasks where the agents hover out of the terrain folds, especially in urban environment.…”