Device and method for measuring rod-shaped article, and device and method for manufacturing 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, and
• an adding process of measuring distances between the intersections adjacent to each other on the outer circumferential edge and calculating the outer circumference by adding the distances between the intersections measured along an entire circumference of the outer circumferential edge.