# Graphic Applications of Unmanned Aerial Vehicles (UAVs) in the Study of Industrial Heritage Assets
## 2 SWOT Analysis Applied to UAV
### Threats  
Finally, different external conditions can affect negatively on the application of UAVs to heritage research. The threats that can be considered in its use are indicated below:  
T1. Risk of damage to third parties. Occasionally, the realization of flights in a confined or reduced space, can produce a collision with an obstacle, like a possible pilot error. The fall of the aircraft can cause damage to people, items and the aircraft itself. Therefore, a prior analysis of the flight environment is required as well as awareness to avoid people's movement under the flight path. Many heritage assets are situated in urban areas, so it is necessary to consider this threat in the UAV use.  
T2. Privacy invasion. The UAV flight allows aerial images to be obtained by overcoming obstacles that are used to protect the privacy of people and property, which is protected by law, despite the fact that the flight takes place over a public space. For the correct use of the UAV in the study of the patrimonial assets it is necessary to obtain the authorization of the owner, as well as an adequate treatment of the information generated from the flight.  
T3. Mobile laser scanning systems. In addition to photogrammetry techniques for 3D model generation, laser scanning technologies have developed new mobile systems that allow scanning reduced spaces with a high accuracy. Nevertheless, a person is still required to move with the capture system. From another point of view, this technology could be equipped on a UAV and both technologies combined.  
T4. Airspace restrictions. UAV flights near airports or military areas are restricted for security reasons. In addition, the flight of the UAV is also restricted in protected natural areas because it may pose a risk to birds. Thus, the area where the patrimonial property is located can limit or prevent its use, and so, the flight could only be done with special permits.  
T5. Complex information processing. The photogrammetry techniques used for the UAV image require a complex analysis process, using specialized software. The laser scanning process directly generates 3D models, using a customized equipment software supplied by the manufacturer, which cost must be considered.  
T6. Non-uniform aeronautical legislation. Different legislations are applied in each country related to UAV flights. This means that the user must know the regulations depending on where the flight takes places. Some countries establish very restricted conditions for the flight of UAVs, especially for foreign users (i.e., Morocco, Brazil, Thailand). On the other hand, the European Union has developed a common regulation for all member countries.  
T7. Pilot qualification and accreditation. To carry out the flight operation, pilots require previous governmental accreditation. Obtaining accreditation depends on the conditions required by each country, however it is common to have to take a course related to UAV management and pass its corresponding evaluation. The FAA in USA or the AESA in Spain are public organisms that establish the requirements to obtain the UAV pilot accreditation.  
In spite of the different threats evaluated, the SWOT analysis has shown that the UAV can be considered an interesting tool for heritage conservation and promotion. Furthermore, the low cost of UAV technology makes it accessible to any user.