User guide

Programming Basics 7-11
> Notice the choices for fiducial finding offered below the video display window.
15. Select the Model Finder method.
16. Click on Next.
> Notice the white-lined box in the video display window. This is the Model
Window, the area which will be defined as the fiducial.
> For our first fiducial, we are going to use the same dot we used to define the
workpiece origin.
17. Using the Position Controls, align the camera crosshairs with the center of the dot.
18. Adjust the Model Size parameters if necessary.
> The Model Window should be as small as possible, but slightly larger than the
fiducial feature.
> You may want to use one half of the dot or a quarter of the dot as the fiducial.
If the fiducial fills the entire Model Window, it is not a good fiducial.
19. Adjust the Search Window parameters if necessary.
> The Search Window is the area in which the Vision System will search for the
fiducial.
> The default values for the Search Window parameters are equal to the
dimensions of the video display window.
20. Adjust the Accept and Confusion Thresholds if necessary.
> Accept Threshold is a minimum “score” that a feature must meet or exceed to
be considered a candidate for the desired fiducial. When the vision system
finds a potential fiducial, it assigns a score to the feature based on the contrast
in the grey-scale. If the score of the potential fiducial does not meet or exceed
the Accept Threshold, the vision system will automatically disregard the
feature and continue searching. Recommended setting: 500-800.
> Confusion Threshold is the maximum score assigned to a “wrong” feature in
the field of view. If multiple features are being considered as a possible
fiducial, a feature that scores greater than the Confusion Threshold will
automatically be accepted as the fiducial. A feature that scores equal to the
Confusion Threshold will be accepted, but only if a higher scoring feature
within the field of view can not be found. The Confusion Threshold should be
set greater than or equal to the Accept Threshold. Recommended setting:
500-900.
21. Click on the Run Time tab.