Three-dimensional LiDAR-Based Point cloud map (3D map) is widely used in varieties of application. In the inspection and survey applications, LiDAR equipment is attached to unmanned aerial system (UAS) for additional perspective of 3D map. Due to the plenteous information and details provided by 3D map, human could find it complicated when comparing between two 3D maps that collected with UAS at the exact location but different in time collected. This paper provides the details of the UAS and LiDAR setup to generate 3D point clouds. Moreover, the object detection algorithm is presented step by step for the obtained point clouds. The experimental results show that the proposed detection algorithm can differentiate the object with the dimension of 2x2x2 meter from two 3D maps successfully while the aircraft flying at the altitude up to 50 meters.