# Remote Image Capture System to Improve Aerial Supervision for Precision Irrigation in Agriculture
## 2 Materials and Methods  
### Description of the Remote Image Capture System (RICS)  
The main objective of the development of the RICS is to create a device that captures images of the region of interest (ROI) of lettuce crops. This RICS is implemented as a remote node that is wirelessly linked with a local coordinator node that processes the captured images. An embedded processor architecture implemented in the local coordinator node, and a cloud server running a web application take control of the whole system [45]. Besides, the system obtains additional information from different sensors installed in wireless nodes, actuators and connection devices. All of them operate together to gather, process and display to the local and remote users all the information related to the performance of the precision agriculture tasks.  
Thanks to the visual monitoring of the crops, periodically capturing images of the ROIs and analyzing them to determine the growth of the plants, it is possible to obtain an estimate of the percentage of vegetation cover, which can be defined as the fraction of land covered by the crop canopy of the plants [46].  
Figure 1 presents a global view of main elements of the proposed system. The remote vision nodes or RICS act as autonomous devices capturing images with their own control logic and power supply. They are connected to the local control node via XBee. This control node performs image storage, processing and transfer to a web server in the cloud. The web server has the Internet access, allowing the clients or remote users to monitor and manage the system.  
The RICS nodes are installed in different measurement stations, located in specific zones of the crop. An outline of the installation of the node in the crop is shown in Figure 2. The RICS box that contains all the electronics is located on a mast fixed to the ground at a height of 1.5 m and with an inclination of 30\({}^{\circ}\) with respect to the horizontal plane. This configuration defines a visual field of the camera, as can be observed in Figure 3. The fixing hardware of the RICS box allows modifying the inclination to change the visual field and therefore the observation area of the crop. The selection of the different sample plots in the crop and the viewing angle determine the portion of the plot that  
Figure 1: Global view of the proposed system. The main components are the in-field remote vision nodes, the local control node web, the web server and the remote clients.  
is monitored. They have to be fixed by the human expert considering the specific characteristics of the crop.  
The remote RICS node stations consist of an A20 or A6C (Ai-Thinker Co. Ltd., Shenzhen, Guangdong, China) camera module (both can be used in the system, since they are compatible) with GPRS and WiFi communication capabilities, a ZigBee radio device for wireless data communication, a power unit (composed of a solar panel, a charger and a battery), as shown in Figure 4. Since the RICS node is the main element of the proposed system, the next sections describe in detail the design and implementation of these nodes.  
Figure 3: Some samples of the images captured by the RICS nodes in a crop of lettuce. Image resolution is 640 \(\times\) 480 pixels. **(a,b,d)** are images of romaine lettuce (_Lactuca sativa_ L. var. _Longifolia_). **(c)** is the image of iceberg lettuce (_Lactuca sativa_ L. var. _Capitata 'Iceberg_').  
Figure 2: Schematic configuration of a remote vision node or RICS box. The placement of the box is configurable and determines the part of the crop that is visible under the area of interest.