Method for monitoring linear dimensions of three-dimensional objects

A method comprising:

• at a 3D measurement system comprising a projector, a computer, a first camera and a second camera, wherein the first camera and the second camera are located at different distances from the projector:
• projecting a known projection pattern that includes at least two non-crossing lines to form a first band and a second band on a surface of an object;
• while projecting the known projection pattern onto the surface of the object:
• recording, using the first camera, a first image of the surface of the object;
• and
• recording, using the second camera, a second image of the surface of the object;
• using the first image acquired by the first camera, determining, by the computer, a first longitudinal coordinate of a first point within the first band and a first vertical coordinate of the first point within the first band, wherein the first vertical coordinate is along a first coordinate axis that is parallel to an optical axis of the projector and the first longitudinal coordinate is along a second coordinate axis that is perpendicular to the optical axis of the projector;
• and
• using the second image acquired by the second camera, determining a second longitudinal coordinate of the first point within the first band and determining a second vertical coordinate of the first point within the first band, wherein the second vertical coordinate is along the first coordinate axis that is parallel to the optical axis of the projector and the second longitudinal coordinate is along the second coordinate axis that is perpendicular to the optical axis of the projector;
• and
• determining a final vertical coordinate of the first point by comparing the first longitudinal coordinate to the second longitudinal coordinate, wherein:
• the final vertical coordinate is determined by adjusting the first vertical coordinate based on a comparison between the first longitudinal coordinate and the second longitudinal coordinate;
• and
• the final vertical coordinate is along the first coordinate axis.