An Image Processing Method for Measuring the Surface Area of Rapeseed Pods

An image processing method that considers pods to be irregular cylinders composed of several oblique cylinder slices with different diameters was proposed to achieve the "highly accurate, highly efficient and large-scale" target of measuring the surface area of rapeseed pods. The total side area of all the oblique cylinder slices, specifically the pod surface area, was calculated. A high-precision 3-dimensional method was used to measure and correct the actual area of the silique for the first time. The results of the measurement accuracy analysis showed that the image processing method could accurately measure the surface area of rapeseed pods. The average measurement error was 2.46%, and the root-mean-square error (RMSE) was 0.92 cm(2). To prove the superiority of this method, we measured the same test samples using four other methods: the Clark formula, the Leng formula, flattening scanning, and quasi-cylinder side area methods. The accuracy and efficiency of the image processing method were much higher than the other four measurement methods. The surface area of multiple pods from 83 rape plants was measured using the image processing method; the results were consistent with the expectations of the experimental design. The 3D measurement and image processing technology were compared and analyzed, and the latter was preliminarily designed for future rape pod seed testing. Thus, this method can provide technical support to measure the surface area of numerous rapeseed pods.