 | Adv. Straight Edge FAQs |
Q: The Reposition Region of Interest and Reference Coordinate System controls are dimmed. How can I make these options available?
Insert a Set Coordinate System step before this step to make the Reposition Region of Interest and Reference Coordinate System controls available.
Q: Why does the step always return a Straightness value of 1?
The step always returns a value of 1 for the Straightness if the selected Detection Method is Best Hough Edge Rake, First Edge Projection, or Best Edge Projection.
The Best Hough Edge Rake detection method finds straight edges by first finding edge points along a Rake and mapping each point to a line in the Hough space. Since each point corresponds to a line in the Hough space, Straightness always has a value of 1.
The First Edge Projection, and Best Edge Projection detection methods find straight lines by projecting a line though a detected edge point. Since the line is projected through the edge point, the point always lies on the line and Straightness always has a value of 1.
The First Edge Rake and Best Edge Rake detection methods detect straight edges by finding edge points along a Rake and fitting a line to the detected edge points. Straightness calculates of how far the detected the edge points deviate from the fitted line.
Refer to the NI Vision Concepts Manual for information about each detection method.
Q: Why does (Legacy) appear next to the specified Detection Method on the property page?
If your inspection was created using Vision Builder AI 3.5, when you open the inspection is Vision Builder AI 3.6 or later, the phrase (Legacy) appears next to the specified Detection Method. This is because the way that the step computes the edge score changed between Vision Builder AI 3.5 and Vision Builder AI 3.6 to more accurately describe the quality of found edges. To provide backwards compatibility, Vision Builder AI still computes the edge score using the original method for inspections created using Vision Builder AI 3.5 and appends (Legacy) to the Detection Method to inform you that the step is using the older method to calculate the edge score.
To update the inspection to use the current edge score calculation, select the desired Detection Method that does not contain the (Legacy) label. If the step no longer detects the correct straight lines in the image, adjust the Minimum Edge SNR until the step located the correct straight lines in the image.