Table Of Contents
Caliper Tool (G Dataflow)
Finds edge pairs along a specified path in the image.
This node performs an edge extraction and finds edge pairs based on specified criteria, such as the distance between the leading and trailing edges and edge polarity.
image in
Reference to the source image.
pixel coordinates
Array containing the coordinates of the pixels to inspect.
You can obtain the pixel coordinates from an ROI descriptor using the ROI Profile node.
edge parameters
Cluster defining the characteristics of the filter used to detect the edges.
contrast
Threshold for the contrast of the edge.
Only edges with a contrast greater than this value are used in the detection process. contrast is defined as the difference between the average pixel intensity before the edge and the average pixel intensity after the edge.
filter width
Number of pixels that the node averages to find the contrast at either side of the edge.
steepness
Slope of the edge.
This value represents the number of pixels that correspond to the transition area of the edge.
subpixel information
Cluster containing information about subpixel analysis.
subpixel accuracy
Number of samples to obtain from a pixel.
interpolation type
Method used to perform the interpolation.
| Name | Value | Description |
|---|---|---|
| quadratic | 1 |
Uses the quadratic formula to compute the pixel location |
| cubic spline | 2 |
Uses cubic splines to compute the pixel location |
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
caliper parameters
Inputs for finding edge pairs.
polarity
Polarity of the leading and trailing edge in the search process.
The following values are possible:
| Name | Description |
|---|---|
| none | Polarity of the edges is ignored. |
| dark-light | The leading edge has a dark-to-light polarity, and the trailing edge has a light-to-dark polarity. |
| light-dark | The leading edge has a light-to-dark polarity, and the trailing edge has a dark-to-light polarity. |
| dark-dark | The leading edge has a dark-to-light polarity, and the trailing edge has a dark-to-light polarity. |
| light-light | The leading edge has a light-to-dark polarity, and the trailing edge has a light-to-dark polarity. |
separation
Desired distance between the leading and trailing edges of an edge pair.
Edge pairs with separation distance outside the range [separation - separation dev., separation + separation dev.] are ignored. If you set this parameter to 0, the node finds all edge pairs.
separation dev.
Tolerance value for the separation between the edges.
This value influences the score of the detected edge pairs.
image out
Reference to the source image.
caliper report
Array of clusters that contain the following information about the detected edge pairs.
edge1 position
Location of the leading edge.
edge1 contrast
Contrast of the leading edge.
edge2 position
Location of the trailing edge.
edge2 contrast
Contrast of the trailing edge.
separation
Computed distance in pixels between the edges in the edge pair.
score
Unused part of report.
edge coordinates
Array of point clusters consisting of the spatial coordinates of the detected edges.
number of edge pairs
Number of detected edge pairs.
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