METHOD AND APPARATUS FOR MEASURING HOT LONG MATERIAL

PROBLEM TO BE SOLVED: To reduce the number of cameras and sensors to be installed, in measuring a length of a hot long material, while ensuing accuracy and reducing equipment cost.SOLUTION: A hot long material measuring apparatus has an imaging field-of-view SA which covers a total length of a hot long material 1, detects that the hot long material has been conveyed in the field of view of one imaging means 5 which images a specific area B of a conveyance path 2 of the hot long material 1, acquires a still picture of the hot long material 1 captured by the imaging means 5 upon detection, and calculates a length of the hot long material 1 on the basis of a longitudinal position of the hot long material in the still picture, and a length conversion factor derived in advance by image-processing light-spot imaging data formed by imaging a light-spot scale arranged in a longitudinal direction of the long material in the specific area B, and different in two or more areas in the longitudinal direction in the image.