## 3 UAV Solutions in Greenhouses  
The use of greenhouses is growing, and thus, the distance between the grower and crop is increasing. New technologies are being introduced for the care and preservation of crops. Obtaining more accurate data on crop growth and local growing conditions shows the grower how and where crop problems arise. In this way, it is easier to understand when and where problems preventing crop productivity are and how to fix them. Unfortunately, current data collection techniques have limited spatial resolution and are labor-intensive [22; 77; 78]. Greenhouse farming is one of the most suitable fields for using robotics, automation and computer technologies together [79]. Most greenhouses have climate control systems, usually consisting of temperature and humidity sensors, as well as irrigation, ventilation and heating systems. Thanks to these systems, it is possible to grow plants in the greenhouse throughout the year. These systems offer a wide variety of possibilities, including climate control and production monitoring. However, they are a costly and complex solution due to cost and reliability issues. The later-emerging wireless sensor networks (WSNs) have become very popular for such projects, with the advantages of modularity, low power consumption, etc. [80]. For this reason, they have been used in greenhouses for monitoring [81] and precision agriculture [82; 83] in many studies. However, in general, such automatic systems do not fully meet the requirements for precise temperature, humidity, etc., settings; therefore, yield losses in greenhouses occur [84]. Although greenhouse solutions with WSNs have been presented in many studies, their application in the greenhouse has been experimentally limited, usually because WSN applications can be used in small-sized areas. For example, [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [81] and [PERSON], [PERSON] and [PERSON] [82] implemented WSNs in small greenhouses. [PERSON] et al. [85] conducted a WSN-based monitoring study in a larger greenhouse but by adding a large number of nodes (wireless sensors). Therefore, they provided a more costly and more complex solution for precision agriculture. The recent activity of UAVs in agriculture has overshadowed the WSN and wheeled agricultural robot solutions. Unlike WSNs, wheeled robots and other solutions, UAVs can take measurements at nearly any point in the three-dimensional space of the greenhouse, making activities such as local climate control and crop monitoring easier and more reliable. Moreover, with the UAV, crops can be monitored continuously at certain times (every week, every hour), and changes in the crop can be monitored. Observing the plants from the air makes it easier to reveal problems such as water stress, soil variation and pest infestation. In addition, thanks to developing camera technology, the disease status of plants that cannot be detected by the human eye can be easily monitored with multiband images by using different sensors (hyperspectral, multispectral, infrared, etc.) [86]. Despite the above-mentioned advantages of UAVs, their use in the greenhouse has been very low in the studies reported to date. Studies on the use of UAVs in the greenhouse have generally focused on the measurement of water vapor (H\({}_{2}\)O), carbon dioxide (CO\({}_{2}\)) and methane (CH\({}_{4}\)), which are three important greenhouse gases [87; 88; 89; 90; 91]. These studies use the advantage of the easy positioning of the UAV in the greenhouse, and they use the  
Figure 5: Distribution maps of banana fusarium wilt: (a) 5-m resolution. (b) 10-m resolution [49]. sensors on the UAV to take measurements in areas that are difficult to measure. However, in these studies, the UAV was manually positioned. Apart from gas measurement, almost no precision agriculture studies have been carried out on applications in the greenhouse, such as crop monitoring, weed detection, yield estimation or plant temperature stress.