- It is hard to control the landing and take-off in urban areas.
•The regulations of air control or even police/military are quite strict for UAV flying over important facilities, infrastructures, pedestrians, since safety is the most important concern for air regulations.
•Geo-referencingthese images with a complex geometry turned out to be a challenging work.
•Electro-magnetic disturbances
•A large amount of tree canopy around the city (DTM measurement)