Table Of Contents
Find Concentric Edge (G Dataflow)
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.
options
Cluster defining the parameters of the edge detection algorithm and the information that is overlaid on the resulting image.
scan direction
Direction in which the node searches for edges along the concentric search lines.
edge options
Parameters used to compute edge gradient information and detect edges.
edge polarity
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 |
kernel size
Size of the edge detection kernel.
Default: 3
width
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
Minimum edge strength, or gradient magnitude, required for a detected edge.
Default: 10
interpolation type
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 |
data processing method
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
show search area
Boolean that specifies if the search area is overlaid on the image.
show search lines
Boolean that specifies if the search lines used to locate the edges are overlaid on the image.
show edges found
Boolean that specifies if the locations of the edges found are overlaid on the resulting image.
show result
Boolean that determines if the edge found is overlaid on the resulting image.
search area color
Color to use to overlay the search area.
search lines color
Color to use to overlay the search lines.
edge locations color
Color to use to overlay the edge locations.
result color
Color to use to overlay the result.
overlay group name
Name to give the overlay group.
image in
Reference to the source image.
ROI descriptor
Region of Interest (ROI) within which the edge detection is performed.
global rectangle
Coordinates of the bounding rectangle for the circular edge in the image.
contours
Individual shapes that define an ROI.
ID
Input that determines if the contour is the external or internal edge of an ROI.
type
Shape type of the contour.
coordinates
Relative position of the contour.
edge fit options
Options that are used to fit the edge.
process
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). |
step size
Distance between concentric search rings.
max pixel radius
Length of the radius within which a point is assumed to be part of the fitted circle.
coordinate system
Input that specifies the coordinate system to use.
reference system
Cluster containing origin, angle (deg), and axis reference.
origin
Point cluster that specifies the origin of the base-reference coordinate system.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
angle (deg)
Angle that the base-reference coordinate system makes with the image coordinate system.
axis reference
Element defined as direct or indirect.
measurement system
Cluster containing origin, angle (deg), and axis reference.
origin
Point cluster that specifies the origin of the base-reference coordinate system.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
angle (deg)
Angle that the base-reference coordinate system makes with the image coordinate system.
axis reference
Element defined as direct or indirect.
error in
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
image out
Reference to the input image.
fitted line
Cluster that contains the position and characteristics of the fitted line.
line segment (pixels)
Intersection of the line equation and the bounding rectangle of the input points in pixels.
point 1
Coordinates for an intersection point.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
point 2
Coordinates for an intersection point.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
line segment (real world)
Intersection of the line equation and the bounding rectangle of the input points in calibrated units.
point 1
Coordinates for an intersection point.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
point 2
Coordinates for an intersection point.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
angle (pixel)
Rotation angle of the detected straight edge, in degrees, measured counter-clockwise from the x-axis extending to the right.
angle (real world)
Rotation angle of the detected straight edge, in degrees, measured along the search direction from the start axis.
straightness
Straightness of the detected edge defined as the root mean squared error of the fitted line that represents the detected straight edge.
average strength
Average strength, or gradient magnitude, of the detected edge.
average SNR (dB)
Average signal-to-noise (SNR) ratio along the detected edge.
line found?
Boolean that indicates if an edge is found.
coordinate system dup
Reference to the coordinate system.
reference system
Cluster containing origin, angle (deg), and axis reference.
origin
Point cluster that specifies the origin of the base-reference coordinate system.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
angle (deg)
Angle that the base-reference coordinate system makes with the image coordinate system.
axis reference
Reference to the axis defined as direct or indirect.
measurement system
Cluster containing origin, angle (deg), and axis reference.
origin
Point cluster that specifies the origin of the base-reference coordinate system.
x
X-coordinate of the center of the circle.
y
Y-coordinate of the center of the circle.
angle (deg)
Angle that the base-reference coordinate system makes with the image coordinate system.
axis reference
Reference to the axis defined as direct or indirect.
error out
Error information.
The node produces this output 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.
Where This Node Can Run:
Desktop OS: Windows
FPGA: Not supported
Web Server: Not supported in VIs that run in a web application