# An Image Processing Method for Measuring the Surface Area of Rapeseed Pods
## 5 Conclusions  
In this study, we proposed an image processing method in which the pod was regarded as an irregular cylinder composed of several inclined cylinder slices with different diameters. We showed that the surface area of the pods could be calculated as the sum of the side areas of all the inclined cylinder slices by calculus, and the corresponding empirical study was also conducted. The application of this method allows for \"highly accurate, highly efficient and large-scale\" measurement of numerous rapeseed pods. \"Highly accurate\" stems from the fact that this method uses image processing technology and calculus principles to transform the pod image into a mathematical model that can be calculated by a computer, which restores the basic characteristics of rapeseed pods. The high-precision 3-D method was first used to measure and correct the actual area of pods, which is also a vital premise to ensure \"high accuracy.\" Our experiment proved that the image processing method is more accurate than the four commonly used methods, such as the Clark formula. \"Highly efficient\" can be explained by the fact that no manual or instrumental measurement is needed for the pods, which only need an orderly arrangement in a suitable background and position for photography. This process is completed by multiple people, which substantially improves measurement efficiency. Currently, pods are arranged and photographed manually during the measurement process. Thus, the measurement efficiency will be  
Figure 10: Design model of rapeseed pod testing machine.  
significantly improved if automatic batch operation by machines can be achieved in the future. \"Large scale\" primarily lies in the achievement of measuring multiple pods. Since an assembly line operation process has been established for placing and photographing the pods, the corresponding photos serve as records, facilitating subsequent inspection, thus avoiding repeated and missed measurements or errors. This study measured the surface area of nearly 40,000 pods from three different rape cultivars subjected to three different fertility treatments. The process did not involve many people, and neither was it time-consuming. The measurement results met the expectations of the experimental design and achieved the measurement aim of \"highly accurate, highly efficient, and large-scale\" for the surface area of rapeseed pods. Therefore, this method provides technical support for the surface area measurement of numerous rapeseed pods.  
Conceptualization, C.G., M.G., H.H. and F.L.; methodology, X.L. and F.L.; software, X.L. and H.X.; data analysis, F.L.; investigation, F.L. and X.L.; writing--original draft preparation, F.L.; writing--review, M.G. and H.H.; funding acquisition, M.G., F.L. and X.L.; All authors have read and agreed to the published version of the manuscript.  
This research was funded by the China Agriculture Research System of MOF and MARA (CARS-13); Hunan Agriculture Research System of DARA, China; the Project from the Department of Education of Hunan Province, China (20C0970); and the Key research projects of Science and Technology Department of Hunan Province, China (2022 NK2047).  
Not applicable.  
The authors declare no conflict of interest.