Circular Edge (Spoke)

Locates the intersection points between a set of search lines within a circular area, such as an annulus and the edge of a circular object. Edges are determined based on their contrast and slope. The function returns the circle that best fits the edges found.

Main Tab

The following controls are available on the Main tab.

• Step Name—Name to give the step.
• Reposition Region of Interest—When enabled, the step dynamically repositions the region of interest based on a coordinate system you built in a previous step.
• Reference Coordinate System—Coordinate system to which you want to link the region of interest.

Settings Tab

The following controls are available on the Settings tab.

• Auto Setup—When enabled, the software locates the strongest edge in the region of interest (ROI) and returns the parameters it used to find the edge.

  Note  Vision Assistant uses the parameters returned by the Auto Setup function to compute the optimal parameters the first time you configure the step. After the optimal parameters are computed, they are saved in the script, and the Auto Setup parameters are disabled. Edits to the step will edit the optimal parameters.

• Search Lines
  • Direction—Direction in which you want the search lines to look for a circular edge within the ROI.
  • Gap—Number of pixels between search lines in the ROI.
  • Edge Strength—Minimum difference in the intensity values between the edge and its surroundings.
  • Smoothing—Number of pixels averaged to find the contrast at either side of the edge.
  • Steepness—Maximum distance in which the edge strength must occur. Steepness characterizes the slope of the edge. Use a higher Steepness value to detect edges in images whose pixel intensities gradually transition from the background to the edge.
• Edge Strength Profile—Edge strength along the search line located in the middle of the ROI.

Results Tab

Displays the results of the edge detection.

• Center X—X-coordinate of the center of the circle.
• Center Y—Y-coordinate of the center of the circle.
• Current Radius—Radius of the circular edge found.
• Current Deviation—Maximum distance found between the points of the edge and the fitted circle.