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Practical Guide to Machine Vision Software: An Introduction with LabVIEW by Steven Ready, Kye-Si Kwon

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7Dimension Measurement

Particle analysis analyzes complete objects rather than a part of an object. So, it is difficult to measure the size of a specific part in an object. On the other hand, the method using edge detection can measure the dimension of parts of objects. In this section, the edge detection method is extended to two dimensions (2D) to measure an object's dimensions. One way to do this is to cover a two-dimensional area with many search lines over which edge detection is performed. The measurement of an object's dimension in this manner can give accurate dimensional information since the outline of an object can be obtained by using a set of line ROIs to define 2D area. The Clamp function based on 2D edge detection is often used to detect locations that define the maximum or minimum length of a part of an object. Then, Caliper function can be used to determine the distances between edges. An example VI of measuring dimension by using a Clamp function can be found from the following folder:

Figure 7.1 shows the front panel of this dimension measurement example. In this example the maximum horizontal size of a hole in an object can be measured. Note that if you change the location and size of the ROI, you can measure the dimension of different parts of the object.

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Figure 7.1 ...

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