3D vision systems are being implemented throughout a number of inspection applications that previously could not be addressed with conventional 2D vision systems. One such 3D system is a laser displacement sensor, which consists of a laser that projects a line and an image sensor, which are both contained in an industrial housing. The object to be measured is moved through the projected laser line and the image sensor captures the displacement of that laser line to extract a three dimensional point cloud of data. This point cloud of data can be used to measure 3D features such as length, width, height, tilt, or volume. It can be used to detect defects, the presence and absence of specific features, or read raised or embossed characters against a low-contrast background. To assist with the extra layer of complexity that 3D inspection brings to machine vision programming, 3D vision programming environments have been upgraded to simplify the process for building maintainable 3D vision applications.
As an example, consider the automotive tire manufacturing process. In the traditional manual inspection process, operators inspect the splice visually and by taking measurements with calipers at regular intervals. The problem with this sampling approach is that problems are often intermittent, which means that a considerable amount of time can elapse before a problem is detected. Even when the operator detects a problem, he or she has no way of knowing whether this is the first or 100th time that it has occurred. Common defects that frequently go undetected include out-of-spec variations in thickness, width and step-height as well as holes, and extra or missing material. A 3D vision system, on the other hand, can detect every defect and it can be configured to immediately stop the splice if a defect is identified so that corrections can be made without wasting any additional material or machine time. Unlike a 2D vision system which relies on lighting to create contrast, a 3D vision system extracts and measures the topography or surface of the body plies to identify, measures and classifies defects as well as determines the width and thickness of the web.