## 3 Results and Discussion
### Measurements Related to Morphological Characteristics of the Plants
It is calculated as follows: \(S=\frac{4+\gamma A}{P^{2}}\). In a similar fashion, the compactness is defined as the total leaf area divided by the convex hull area. The subscripts \"_man_\" and \"_exp_\" are used in the previously referred parameters to indicate the manual calculation and experimentally (automatically) computed values, respectively. Table 7 summarizes the averages (mean and standard deviation of the outcomes) of all metrics and measured parameters depicted in Table 6 for the 4-week experiment. Specifically, for the case of the diameter (\(D_{man}\) and \(D_{exp}\)), stockiness (\(S_{man}\) and \(S_{exp}\)), and compactness (\(C_{man}\) and \(C_{exp}\)) parameters, the mean and the standard deviation of the absolute difference between the manual and the experimentally calculated values are reported with the symbols \(D\), \(S\), and \(C\), respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Day** & **Plant No. ** & **IoU** & **Precision** & **Recall** & **F1 Score** & \(m_{dt}\) & \(c_{dt}\) & \(D_{man}\) & \(D_{exp}\) & \(S_{man}\) & \(S_{exp}\) & \(C_{man}\) & \(C_{exp}\) \\ \hline \multirow{6}{*}{Day 10} & A & 0.952 & 0.99  
In Figure 18, as an illustrated example, some of the lettuce plants' parameters that were measured over time (in days) for the 4-week experiments are presented. The measurements were conducted manually and automatically for all five plants labeled A to E, with the data collected once per week. The parameters of the lettuce plants shown in the figure include the total projected leaf area (Figure 18a,b), the maximum diameter (Figure 18c,d), the compactness (Figure 18e,f), and the stockiness (Figure 18g,h) for both manual and automatic calculations in each instance. Figure 18: An example of the measured plant dimensions (both manually and automated) as a function of time (in days) for the 4-week experiments and for all the five plants denoted with the letters A to E. The measurements were performed once every week. The lettuce parameters depicted in the figure concern the total projected leaf area (**a**,**b**), the maximum diameter (**c**,**d**) the compactness (**e**,**f**), and the stockiness (**g**,**h**) for the manual and the automatic calculations, respectively, for each case, (colored figure online). In Figure 19, the detailed visual representation of the detected and ground truth total projected leaf areas overlaid, for all the plants in the 4-week experiment, is presented. The areas' plots were created as solid polygonal regions defined by 2D vertices. These vertices correspond to each lettuce's total projected leaf area contour, either manually traced or found experimentally. In the first 2 rows (Days 10 and 17), the detected (experimental) area is clearly visible with a different color (lighter shade of pink), so as to emphasize the difference in the detection of the plant by our algorithmic procedure. In the last two weeks (Days 24 and 31), the corresponding overlaid, experimentally delineated area of the plant is almost identical to the ground truth and cannot be visually differentiated. This fact is also justified by the assessment criteria outlined in Table 6 for the specified experimental period, which indicate high confidence scores for IoU, Precision, Recall, and F1-score metrics. This can be attributed to the laboratory experimental conditions under which the images were acquired, e.g., the mosaic pattern in the background floor but especially the organic fertilizer used to facilitate lettuce growth. This latter fact is proved from the results after processing the first two weeks' images (Days 10 and 17), also affecting the detection accuracy. On Days 24 and 31, where lettuce are fully grown and cover the pot, the detection results for the leaf contours are almost the same as the ground truth images, as is clearly depicted from the last two rows of Figure 19. Both contours are almost identical for each plant. Another factor that can affect the segmentation result is the presence of gravel in the soil.