Hardware manual

Impact Reference Guide Subpixel Edge Extractor
3-143 Datalogic Automation Inc.
surement Length displayed is 100, but the distance in the real world is 200. Enter 200 in the Train
Measurement Length field and click Train. The tool calculates the Scale Factor so that the measured
distance in pixels (the Measurement Length) equals the Train Measurement Length. The Scale Factor
is applied after any camera calibration factor. The Reset button resets the Measurement Length and
Scale Factor to their original values.
2. Enter the Measurement Tolerances: In the Nominal field, enter the correct measurement length, then
enter the tolerances in the Minus and Plus fields.
Subpixel Edge Extractor
In the Measurement Drawer
The Subpixel Edge Extractor tool finds the edge points along the edge of an arbitrary shape with subpixel
accuracy. See “Edge Extraction Examples” on page 3-144.
Input Name What it is
Input Image Linked Image
Tool Origin The tool’s origin relative to the entire image space
Wide Line ROI Indicates the direction and limits of the edge search
Edge Polarity Search for rising or falling edges
Edge Number To
Extract
The edge number to extract.
Maximum Number
of Edge Crossings
Limits the number of edges found to those with the strongest transitions.
Edge Detection
Method
Gradient Edges or Grey Level Edges
Gradient detection generally provides more consistent results. In some
cases Gradient detection can pick up extra edges in a noisy image and
Grey Level detection may offer better control.
See “Edge Detection Method” on page 3-78.
Edge Detection
Sensitivity
Determines the transition level necessary for detection. A higher value
detects more edges.
Non-fixed selections use adaptive threshold selection.
Fixed Threshold uses the Fixed Gradient Threshold Percentage value or
the Fixed Grey Level Threshold Percentage (depending on the Edge
Detection Method)
Fixed Gradient
Threshold Percent-
age
The threshold value used when Gradient Edge Detection and Fixed
Threshold Edge Detection Sensitivity are selected