基于多轮廓模型的红枣体积和表面积在线测量方法.

Ample sunshine, together with scarce rainfall and large variation in diurnal temperature, makes Xinjiang a unique place for producing tasty red jujube in China. Grading is an important parameter for storing and processing the jujube to maximize its market value, and needs to measure its volume and surface area. Traditional methods for measuring fruit volume are spheroid-like to measure the volume of water the fruit displaces when being immersed into water, with the surface area measured by peeling or slicing. These methods are inefficient and cannot be used for real-time measurement. The aim of this paper is to present a real-time multi-contour model to estimate the volume and surface area of the red jujube. We assessed the effect of contour angles, projection heights and diameters on the ultimate results. In the proposed method, 2D images of the targeted jujube were captured on a rotating circular table using a camera, and the contour of the images was then extracted using image processing. A 3D multi-contour model was developed based on the extracted 2D contour, and it was then used to estimate the volume and surface area of the targeted jujube. The result showed that the diameter of the target estimated by the multi-contour sphere model did not change, and that with an increase in the relative errors between the contours angle and the projection height, the volume estimated by the model increased (with the minimum relative error being 6.0%) while the error of the estimated surface area decreased (with the minimum being 1.0%). The angle between the contour and the projection height in the multi-contour sphere model had a prescribed value, and the relative error of the volume and surface area estimated by the model varied with the diameter in that the smaller the diameter was, the bigger the errors were. The average mean square error and the average relative error of the volume and surface area estimated by the model were 2.45 cm³ and 10.2%, and 3.65 cm² and 7.09%, respectively. An increase in grading appeared to increase the average relative errors of the estimated volume but had no noticeable impact on other factors. In summary, the multi-contour model for real-time measuring the volume and surface area of the red jujube offers an alternative to grading the jujube although further improvement is needed to reduce the errors. [ABSTRACT FROM AUTHOR]