Machine Vision

The simplest type of vision system is one that senses only along a line. These one-dimensional sensors function best when used to simply detect the presence or absence of an object, and generally make no further attempt at interpretation. Typically, these are used in applications such as automated assembly line counters, where perhaps the number of bottles passing by a particular point needs to be monitored. The light passing from one side of a conveyer belt to a detector on the other side is occluded when a bottle passes by. This break in the light signal is then recorded electronically and another unit is added to the total count.

Along with the simplicity of this system, unfortunately, comes its limited applicability. This system (like most other one-dimensional scanners) is not very good at distinguishing between different objects. Two different-shaped bottles, for example, can not be identified from one another. A pickle jar, a hand, or a large flying insect may trigger this system to record the break in light as another bottle. Although they tend to be inexpensive, the limited abilities of one-dimensional vision systems make them popular choices for only very specific, well-controlled applications. For the more sophisticated sensing requirements of most vision applications, two-dimensional techniques need to be employed.