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Directory of Commercial Providers of this Technology ...
RE Technology Comparison Chart ...
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An important basic distinction among digitizing technologies is between contacting and non-contacting instruments. Contacting digitizers, or touch-probes, are often very accurate over a wide measurement volume, and some instruments in this class are among the most affordable devices available. There are contact digitizers that are positioned manually to yield a single measurement at a time, or may be scanned across a surface to produce a series of measurements. There are also touch probe instruments available which can automatically scan an object using a variety of mechanical drive means. Contact instruments are often in the form of an articulated arm that allows for multiple degrees of freedom of movement. The position of each section of the arm is determined by encoders, glass scales, or in the case of the more inexpensive devices, by potentiometers mounted in each joint. Other mechanical arrangements besides arms are also used.
On the down-side, contacting devices can distort soft objects such as auto upholstery, and are too slow to digitize parts of human bodies, or may require much labor to scan complex curved surfaces. On the other hand, they are not affected by the color of a surface or if it is transparent or reflective, the way laser and other light-based systems may be. And while slow, they may actually be the fastest way to digitize simple surfaces where just a few data points need be gathered. Manually positioned devices can also make it easier to get at hard to digitize areas of an object such as narrow slots or pockets.
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Mechanical Touch-probe Systems