User Manual

7-10 Programming Basics
16. Click on Done.
> Now you are asked to select the method for defining the first fiducial.
> Notice the choices for fiducial finding offered below the video display
window.
17. Select the Model Finder
Model FinderModel Finder
Model Finder method.
18. 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.
19. Using the Position Controls, align the camera crosshairs with the center of the dot.
> Notice the tabs below the video display, Image, Run Time and Model Finder.
20. 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.
21. 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.
22. 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 how well it
matches the previously taught model. 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 that could be assigned to a
“wrong” feature in the field of view. If a feature scores higher than the
Confusion Threshold, the Vision System concludes that it must be the correct
feature and immediately terminates the search. If a feature scores above the
Accept Threshold, but below the Confusion Threshold, the Vision System
will flag the feature as a “candidate” match, but will continue searching for a
better match. The Confusion Threshold should be set greater than or equal to
the Accept Threshold. Recommended setting: 500-900.