Automatic measurement of cow linear appraisal indicators based on two-stage key point locating algorithm

Aiming at solving the problems of the traditional measurement methods of cow linear appraisal indicators, such as subjective influence, low degree of automation, and errors in locating the key points of linear appraisal, an automatic measurement method of cow linear appraisal indicators based on two-stage key point locating algorithm was proposed. For the depth image sequence of the cow back, the edge smoothing and missing area repairment were performed based on filtering method.Then, the key area detection algorithm based on YOLO v5 was used to determine the key areas of linear appraisal and reconstruct the 3D point cloud model of relevant area. Next, the key points of linear appraisal were located by calculating the regional point cloud curvature and the maximum value of z-axis.Finally, the linear appraisal indicators were obtained according to the relative position of key points. The experimental results showed that the method could accurately measure the body length, shoulder width, chest width, belly width and waist width indicators of dairy cows from an overhead perspective.For the five linear appraisal indicators of 15 dairy cows, the average absolute error was 1.55 cm, the root mean square error was 1.78 cm between the algorithm measurement value and the actual measurement value, and the maximum coefficient of determination R~2 was 0.9394. The experiment proved that the method could realize the accurate measure-ment of cow linear appraisal indicators in the actual breeding environment, which had certain practical significance for production.