Find Circle 2D

Function Description

Detect the center of circles in an image.

Use Cases

A general circle detection step with no fixed usage.

Input

  • Color: The center of circles in the image input via this port will be detected.

Output

  • Color Map: Outputs a color image for visualizing the detection results.

  • Circles: Outputs the center coordinates and angle data of the detected circles.

  • Radius: Outputs the radius of the detected circles.

Parameter Description

Output Settings

  • Output Type

    Sets the data type of the circle detection result.

    Value List: Shape2DList (default), Pose2DList

Circle Detector Settings

  • Circle Similarity

    Threshold for the similarity between a candidate target and an ideal circle. A higher value requires the detected shape to be closer to a perfect circle.

    Default: 0.5

    Tuning tip: The range is 0 to 1. If the workpiece has gaps, deformation, or partial occlusion, lower this value appropriately.

  • Min Center Distance

    When multiple circles exist in an image, limits the minimum pixel distance between the centers of any two detected circles. This prevents the same physical circle from being detected and output repeatedly.

    Default: 50 px

  • Min Repeatability

    During multi-threshold slicing, the minimum number of different binarization layers in which the same connected component must be continuously extracted before it is confirmed as a valid circle center. This parameter verifies feature stability. A higher value improves the ability to filter random noise or weak false edges.

    Default: 2

    Tuning tips:

    • If weak target contrast causes frequent missed detections, try reducing it to 1.

    • If the background contains substantial noise and causes false detections, increase it appropriately, such as to 3 or 4. Usually reduce Threshold Step at the same time so that enough layers are available for verification.

  • Enable Polarity Filter

    When enabled, specifies the target color polarity (black or white). When disabled, both polarities are searched.

    Default: Disabled

  • Enable Convexity Limit

    When enabled, limits the ellipticity range of detected targets to filter holes that are approximately circular.

    Default: Disabled

Threshold Settings

  • Threshold Step

    Sensitivity threshold for dynamically adjusting the step. The step-adjustment mechanism is triggered when the change exceeds this threshold.

    Default: 10, a balanced value for scenes of medium complexity.

  • Min Threshold

    Minimum effective value for step adjustment, preventing an overly small step from causing slow convergence.

    Default: 20, the minimum step size for basic accuracy.

  • Max Threshold

    Maximum allowed step size, preventing excessive steps from causing system oscillation or calculation overflow.

    Default: 200, the maximum step boundary balancing efficiency and stability.

Circle Radius Settings

  • Min Radius

    Lower bound for the radius of circles to detect. Circle features smaller than this radius are ignored.

    Default: 10 px

  • Max Radius

    Upper bound for the radius of circles to detect. Circle features larger than this radius are ignored.

    Default: 200 px