The past few columns about inspection and measurement have led to discussion of different systems for measuring based on images. One type of measurement done via image analysis is dimensional, or coordinate, measurement. The systems are called video, or vision measuring, systems. Here is a basic description of what these systems are and how they are used.
Why video measurement?
Video measurement is noncontact. Only light touches the part. A magnified image is measured. Video measurement is good for big parts, too. Scales and encoders track the positions of measured points anywhere across a part, even when those points are measured at the highest magnifications. Video measurement can be fast. CNC-based systems with metrology software can measure widely spaced coordinates on a part in seconds. Video measurement is accurate. Micron-level accuracy and repeatability are increasingly common. Video measurement excels in measurements in a plane, and it can also measure in three dimensions. Video measurement is versatile. It can measure parts made of virtually any material. Video measurement lets manufacturers ensure that processes are under control and that parts are within specification.

The proper level

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