Hardware manual

Circular Pattern Find Impact Reference Guide
Datalogic Automation Inc. 3-70
The average of all grey levels within the Region of Interest is calculated. The Fixed Threshold Range (i.e.
the difference between the Min and Max values) is centered on the average grey level. Pixels with grey lev-
els within that range are considered in-range of the inspection. For example, if the Fixed Threshold Range is
20 to 40, the range is 20. If the average grey level is 70, the center of the grey level is 35. All pixels with
grey levels between 25 and 45 (35 - 10 and 35 + 10) are considered in-range.
Output Origin
The output origin is located based on the centroid of the filtered blobs. This means that the found output ori-
gin is based on the blobs that pass based on the filter settings. If there are multiple blobs, then the origin is
located based on their combined centroid. In most cases you want to filter all but one blob. If that blob is not
found, then set the tool to fail based on a minimum blob count of one. In other cases, you want to set the fil-
ters so that all the blobs pass and base the output origin on their combined centroid, especially if the blobs
may break up.
Centroid X, Y and Major Axis Angle type: The origin angle is the Major Axis of the blob, and, because the
major axis is a line with two directions, the tool chooses the angle between -90 and 90 degrees.
Centroid X, Y, and Major Axis Angle 360 Range type: The origin angle is the Major Axis of the blob, and,
because the major axis is a line with two directions, the tool chooses the angle on the side of the blob that
extends furthest from the centroid (the longer side).
Circular Pattern Find
In the Locating Drawer
The Circular Pattern Find tool can quickly find the rotational position of rotating objects, such as coins, bot-
tle caps, or snap rings. It uses normalized correlation over a circular arc and outputs an origin centered on the
circle. The tool can be trained on and can search part or all of the circular arc. It can find one or several
matches around the circular arc.
The tool has one circular arc ROI. To set up the tool, place and size the circular arc ROI over the region to be
inspected and click the train button. If necessary, resize the arc length to cover the desired search angles. If
the train region is 360 degrees, it is not necessary to resize the arc length. If train region is less than 360
degrees, the ROI length can be resized up to 360 degrees.
To adjust the circular arc ROI move the cursor around the ROI border until the cursor changes to the desired
type, then click and drag the cursor to the desired place and size.
• Move
• Increase Angle
• Increase Radius
Average Grey Level
Threshold Min Threshold Max