Method and apparatus for pattern matching with active visual feedback

An apparatus and method for cutting pieces of material from a workpiece (18), such as a web of patterned fabric, which includes irregularities or which is misaligned with respect to a coordinate system of the cutting apparatus. The workpiece is spread on a cutting table (12, 102) where it is cut by a numerically controlled cutter (24, 28, 30) in accord with an electronic marker stored in the cutter controller. The marker is matched to the workpiece and appropriate adjustments are made to the marker before the workpiece is cut. A laser (42), operatively connected to the controller, projects a match target (61) onto the workpiece at a point corresponding to a selected point on the marker. The marker is then adjusted such that the selected point coincides with a desired location on the workpiece. Adjustment is achieved by electronically displacing the match target from a non preferred location to a preferred one. Software in the controller translates this displacement into appropriate adjustments to the marker. The displacement is effected with an electro-magnetic pointing device (46) which coacts with a digitizing grid (44) embedded in the cutting table work surface and operatively connected to the controller.