A three-dimensional measurement method of geometric parameters of a rope or a cable provides for obtaining a three-dimensional representation of a plurality of 3D contour points of the rope or cable and calculating the geometric parameters thereof, such as diameter, roundness and axis. A calibrated three-dimensional optical measurement system for measuring geometric parameters includes a plurality of digital image acquisition devices and a digital image processing device configured to perform the steps of the three-dimensional measurement method.

A three-dimensional measurement method of geometric parameters of a rope or a cable provides for obtaining a three-dimensional representation of a plurality of 3D contour points of the rope or cable and calculating the geometric parameters thereof, such as diameter, roundness and axis. A calibrated three-dimensional optical measurement system for measuring geometric parameters includes a plurality of digital image acquisition devices and a digital image processing device configured to perform the steps of the three-dimensional measurement method.

A phase calculation unit (12) calculates, as a first phase, a deflection angle of a first similarity vector having a first similarity and a second similarity calculated by a similarity calculation unit (11) as elements. The phase calculation unit (12) calculates, as a second phase, a deflection angle of a second similarity vector having a third similarity and a fourth similarity calculated by the similarity calculation unit (11) as elements. A period calculation unit (13) calculates a period of a pattern formed on a long body on the basis of the first phase and the second phase calculated by the phase calculation unit (12). An abnormality detection unit (14) detects an abnormality in the long body on the basis of the period calculated by the period calculation unit (13).

An armored DSS cable includes: an inner layer part including a first rope helically wound; and a surface layer part including an optical fiber module and a plurality of third ropes, the optical fiber module having an optical fiber and a plurality of second ropes helically surrounding the optical fiber and having a smaller outer diameter than the first rope, the third ropes having a larger outer diameter than the first rope, such that the optical fiber module and the third ropes are arranged on an identical circle and helically wound, wherein the inner layer part and the surface layer part are formed concentrically.

A phase calculation unit (12) calculates, as a first phase, a deflection angle of a first similarity vector having a first similarity and a second similarity calculated by a similarity calculation unit (11) as elements. The phase calculation unit (12) calculates, as a second phase, a deflection angle of a second similarity vector having a third similarity and a fourth similarity calculated by the similarity calculation unit (11) as elements. A period calculation unit (13) calculates a period of a pattern formed on a long body on the basis of the first phase and the second phase calculated by the phase calculation unit (12). An abnormality detection unit (14) detects an abnormality in the long body on the basis of the period calculated by the period calculation unit (13).