Version:

Last Modified: June 25, 2019

Finds a straight edge in an annular search region of an image.

This node locates the intersection points between a set of annular search lines and the edge of an object.

Cluster defining the parameters of the edge detection algorithm and the information that is overlaid on the resulting image.

Direction in which the node searches for edges along the concentric search lines.

Parameters used to compute edge gradient information and detect edges.

Polarity of the edges to be found.

Name | Value | Description |
---|---|---|

all edges | 0 |
(Default) Searches for all edges |

rising edges | 1 |
Searches for rising edges |

falling edges | 2 |
Searches for falling edges |

Size of the edge detection kernel.

**Default:
**3

Number of pixels averaged perpendicular to the search direction to compute the edge profile strength at each point along the search ROI.

**Default:
**3

Minimum edge strength, or gradient magnitude, required for a detected edge.

**Default:
**10

Interpolation method used to locate the edge position.

Name | Description |
---|---|

zero order | Rounds to the nearest integral edge location |

bilinear | Uses bilinear interpolation to compute the edge location |

quadratic | Uses the quadratic formula to computer the edge location. |

cubic | Uses cubic splines to computer the edge location. |

bilinear fixed | (Default) Uses the fixed-point computation of bilinear interpolation to determine the edge location |

Method used to process the data extracted for edge detection.

Name | Description |
---|---|

average | Averages the data extracted for edge detection |

median | Takes the median of the data extracted for edge detection |

**Default:
**Average

Boolean that specifies if the search area is overlaid on the image.

Boolean that specifies if the search lines used to locate the edges are overlaid on the image.

Boolean that specifies if the locations of the edges found are overlaid on the resulting image.

Boolean that determines if the edge found is overlaid on the resulting image.

Color to use to overlay the search area.

Color to use to overlay the search lines.

Color to use to overlay the edge locations.

Color to use to overlay the result.

Name to give the overlay group.

Reference to the source image.

Region of Interest (ROI) within which the edge detection is performed.

Coordinates of the bounding rectangle for the circular edge in the image.

Individual shapes that define an ROI.

Input that determines if the contour is the external or internal edge of an ROI.

Shape type of the contour.

Relative position of the contour.

Options that are used to fit the edge.

Type of search performed.

Name | Description |
---|---|

get first edge | Returns the first edge. |

get first + last edge | Returns the first and last edge. |

get all edges | (Default) Returns all edges found along the search path(s). |

Distance between concentric search rings.

Length of the radius within which a point is assumed to be part of the fitted circle.

Input that specifies the coordinate system to use.

Cluster containing
**origin**,
**angle (deg),**
and
**axis reference**.

Point cluster that specifies the origin of the base-reference coordinate system.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Angle that the base-reference coordinate system makes with the image coordinate system.

Element defined as
**direct**
or
**indirect**.

Cluster containing
**origin**,
**angle (deg)**, and
**axis reference**.

Point cluster that specifies the origin of the base-reference coordinate system.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Angle that the base-reference coordinate system makes with the image coordinate system.

Element defined as
**direct**
or
**indirect**.

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an
**error in**
input and an
**error out**
output so that the node can respond to and communicate errors that occur while code is running. The value of
**error in**
specifies whether an error occurred before the node runs. Most nodes respond to values of
**error in**
in a standard, predictable way.

**Default:
**No error

Reference to the input image.

Cluster that contains the position and characteristics of the fitted line.

Intersection of the line equation and the bounding rectangle of the input points in pixels.

Coordinates for an intersection point.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Coordinates for an intersection point.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Intersection of the line equation and the bounding rectangle of the input points in calibrated units.

Coordinates for an intersection point.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Coordinates for an intersection point.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Rotation angle of the detected straight edge, in degrees, measured counter-clockwise from the x-axis extending to the right.

Rotation angle of the detected straight edge, in degrees, measured along the search direction from the start axis.

Straightness of the detected edge defined as the root mean squared error of the fitted line that represents the detected straight edge.

Average strength, or gradient magnitude, of the detected edge.

Average signal-to-noise (SNR) ratio along the detected edge.

Boolean that indicates if an edge is found.

Reference to the coordinate system.

Cluster containing
**origin**,
**angle (deg)**, and
**axis reference**.

Point cluster that specifies the origin of the base-reference coordinate system.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Angle that the base-reference coordinate system makes with the image coordinate system.

Reference to the axis defined as
**direct**
or
**indirect**.

Cluster containing
**origin**,
**angle (deg)**, and
**axis reference**.

Point cluster that specifies the origin of the base-reference coordinate system.

X-coordinate of the center of the circle.

Y-coordinate of the center of the circle.

Angle that the base-reference coordinate system makes with the image coordinate system.

Reference to the axis defined as
**direct**
or
**indirect**.

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

**error in**
input and an
**error out**
output so that the node can respond to and communicate errors that occur while code is running. The value of
**error in**
specifies whether an error occurred before the node runs. Most nodes respond to values of
**error in**
in a standard, predictable way.

**Where This Node Can Run:
**

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application