Method and apparatus for cutting out pieces from a fabric having a repetitive design thereon

A method of cutting out pieces for assembly together, said pieces being cut out from sheet material having a design thereon which is regularly periodic in at least one direction, such as a length of fabric having a checked pattern thereon, the method serving to establish continuity or alignment in the design when at least two of the pieces are assembled, with the positions of the pieces on the length of fabric being previously determined for at least two of the pieces and including a margin which is not less than one half of a design element in at least one direction, the method comprising the following steps:

• (a) disposing a length of fabric on a cutting-out table;
• (b) storing shapes, positions, and orientations of the pieces to be cut out in a computer system memory, with a margin corresponding to at least one half of a design element being reserved between outlines of said at least two pieces in at least one direction;
• (c) selecting and storing points (A,B) on edges of said at least two pieces which must coincide upon assembly;
• (d) taking a pair of images of said length of fabric, with each image being substantially centered over a corresponding one of said points, using a camera connected to said computer system and disposed over said length of fabric, with co-ordinates of the camera in a frame of reference relating to the cutting-out table being controlled by said computer system;
• (e) displaying the two images on a screen to observe any offset between adjacent design elements at said edges whereat said points lie, in particular by juxtaposing or superposing the designs of the images;
• (f) correcting any observed offset by means of an input accessory to said computer system to establish design continuity between said images in said at least one direction, and
• (g) storing correction parameters of said offset in the computer memory to define a new cutting-out program in which design continuity is ensured when said pieces are assembled.