Automatic identification of articles having contoured surfaces

Abstract

An automated identification system comprises a first classification station which uses two laser sources and video imaging techniques to identify and distinguish between similar items such as, for example wooden cabinet doors and drawer fronts. Each laser produces a fan-shaped plane of light, perpendicular to the other, on front face of the door. The fan shaped planes of light produce a first profile stripe in the horizontal direction across the width of the door face and a second profile stripe in the vertical or length direction. A first video camera captures the image of the profile stripe across the width of the door. A second camera is used to capture the profile stripe in the vertical direction to determine whether the panel shape is square or cathedral shaped. A feature-based approach is used to process the captured profile stripes and compare them to a library of known profiles. A third camera, placed substantially parallel to the first camera captures the width measurement of the door. Finally, the length of the door is determined with the aid of a photoelectric sensor which senses the time it takes for the door to pass a point along a moving conveyor. Once the style of the door is determined, the door may pass through a next station where a color camera is used to determine the color of the door. Thereafter, a label identifying the style, size, and color of the door may be affixed to the door prior to shipping.