Table Of Contents

Line Gauge (G Dataflow)

Last Modified: October 26, 2017

Measures the distance between selected edges with high-precision subpixel accuracy.

You can use different measurement modes with this node, such as measuring distances between points and edges and vice versa. This node also can step and repeat its measurements across the image. Depending on the type of the measurement, this node first determines the relevant edges in the image before computing the distances.

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initial reference

Base coordinate system.

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origin

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

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angle (deg)

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

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axis reference

Element defined as direct or indirect.

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subpixel options

Cluster containing the options for subpixel analysis.

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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

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subpixel accuracy

Number of samples to obtain from a pixel.

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image in

Reference to the source image.

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line coordinates

Array specifying the pixel coordinates that form the end points of the line.

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edge parameters

Cluster defining the characteristics of the filter used to detect the edges.

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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.

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filter width

Number of pixels that the node averages to find the contrast at either side of the edge.

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steepness

Slope of the edge.

This value represents the number of pixels that correspond to the transition area of the edge.

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measurement type

Type of measurement to perform.

Subpixel information is not used when measuring distances between points.

Name Description
edge to edge Measures the distance between the first and last edge locations along a line in the image.
edge to point Measures the distance between the first edge in the image and the end point of a line.
point to edge Measures the distance between the start point of the line and the first edge along the line of the image.
point to point Measures the distance between two points in the image.
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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.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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offset array

Array of point clusters that specifies the shift in the start and end points of the pixel coordinates.

The offset array is used for repeating the measurement across the image.

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new reference

New coordinate system.

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origin

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

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angle (deg)

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

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axis reference

Element defined as direct or indirect.

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image out

Reference to the source image.

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distances

Array containing the measured distances.

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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.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

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


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