Measuring device and measuring method for rod-shaped article, and manufacturing device and manufacturing method for rod-shaped article

A rod-shaped-article measurement method that is a measurement method for measuring an outer circumference of a rod-shaped article in a transport section in which the rod-shaped article is transported, the measurement method comprising:

• an imaging step of capturing an image of an end surface of the rod-shaped article;
• and
• an image processing step of calculating the outer circumference by processing the image captured in the imaging step,
• wherein the image processing step includes
• an edge identification process of identifying an outer circumferential edge of the end surface in the captured image,
• an intersection identification process of creating an imaginary circle based on the outer circumferential edge, creating n straight lines passing through a center point of the imaginary circle, and identifying two intersections at which each of the straight lines crosses the outer circumferential edge,
• a first calculation process of measuring a distance between the two intersections for each of the straight lines and calculating an imaginary diameter of the outer circumferential edge by dividing a sum of the distances between the intersections by n, and
• a second calculation process of calculating the outer circumference by multiplying the imaginary diameter by π.