# Graphic Applications of Unmanned Aerial Vehicles (UAVs) in the Study of Industrial Heritage Assets
## 3 Methodology for the UAV Use in Graphic Application  
In this section, a general methodology for the UAV use in graphic application for a set of heritage assets is proposed. A general methodology can be considered with the follow steps (Figure 2):  
1. Selection and identification of the heritage assets. The initial step is the asset selection, considering the objective of the case study of interest. In the field of industrial heritage, the traditional or singular manufacturing activities of a region and the relationship between its heritage elements often generate special interest. 2. Heritage assets location. A Geographical Information System (GIS) or some other map analysis system (i.e., Google Maps) is required to know where the assets are located. These systems establish geographical coordinates (latitude, longitude) or Universal Transverse Mercator (UTM) that allows the positioning of heritage assets. In addition, the extent of the terrain and environmental around the assets can be considered on the selection of the UAV model. 3. Flight restrictions. Most countries have UAV flight regulations. In general terms, UAV flight is restricted near airports, in urban areas and in protected environments, for security reasons. In addition, the weight of a UAV is another variable to consider within the regulation. Thus, the level of restriction and the need for local government authorization depend on the area to be overflow and the characteristics of the UAV. 4. Heritage asset visits. An initial visit to the assets is required to identify the key details. This allows to decide the elements that will be captured, due to the special interest that they represent. On the other hand, the existence of possible obstacles in the flight of the UAV can be controlled, allowing to define the most appropriate position of the pilot. Finally, it makes it possible to analyse the conservation status of the assets. These characteristics should be considered when selecting the UAV model. 5. UAV model selection. The stability of the flight, the quality of the camera and the size and weight of the UAV must be taken into account to select the most appropriate model for the analysis of a particular heritage asset. Low weight reduces the need for flight authorizations and small size facilitates flight between possible obstacles and in small areas. However, the stability can be affected by the wind, making it difficult to take pictures during the flight. Multi-rotor UAVs are often considered an appropriate typology due to the wide variety of existing models. However, the fixed-wing UAV topology is more appropriate for analysing a large terrestrial extension, due to the low battery life of multirotor UAVs. 6. Flight plan. A flight plan is required to ensure proper execution. The plan will include a selection of items to photograph and the video recording area. Due to the low battery life, several flight operations are often required. The plan will structure the actions to be carried out in each flight operation, so the number of batteries required must be estimated beforehand. In addition, the position of the pilot will be decided on the basis of the actions to be carried out. Finally, the necessary safety measures shall be considered in order to reduce the risk of accidents. 7. Flight execution. Prior to the flight operation, climatic conditions must be analysed. High wind speed, rain or poor visibility will prevent its execution. Good weather conditions allow the flight operation and so, the planned actions could be carried out. 8. Information processing and data analysis. Finally, the image obtained can be analysed relating the asset with the environment where is situated, or with other assets located in the immediate vicinity. Additionally, video editing actions to promote the asset or conservation actions can be considered.