Measuring accurately-does your calibration technique get the job done?

When measuring it is important to understand all of the factors which effect accuracy. Using a vision system to measure is no different. Proper selection of the system components is not enough. It is true that most vision systems have the internal capability to extract measurements using sub-pixel techniques, but one should not be fooled into thinking one's system is actually that accurate if one fail to compensate for system induced distortions. Understanding these potential errors and then correcting for them is a necessary step in making sure one is measuring absolutely and not relatively.