IMAQ Find Edge 2 VI

NI Vision 2019 for LabVIEW Help

Edition Date: March 2019

Part Number: 370281AG-01

»View Product Info
Download Help (Windows Only)
Requires: NI Vision Development Module

Finds straight edges (lines) within a region in an image.

Note  Setting the bit depth as 0 for 16-bit and SGL images is invalid and doing so will produce an error.

Supported Image Types

8-bit unsigned grayscale 16-bit unsigned grayscale 32-bit RGB 16-bit signed grayscale 64-bit RGB floating point grayscale 32-bit HSL

IMAQ Find Edge 2

/images/reference/en-XX/help/370281AG-01/ccclst.gif

Options is a cluster defining the parameters of the edge detection algorithm and the information that is overlaid on the result image.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Search Direction specifies the direction in which the Region of Interest (ROI) is examined when straight edge detection is performed.

Left to Right (0)

(Default) Searches for edges from left to right

Right to Left (1)

Searches for edges from right to left

Top to Bottom (2)

Searches for edges from top to bottom

Bottom to Top (3)

Searches for edges from bottom to top

/images/reference/en-XX/help/370281AG-01/cnclst.gif

Edge Options specifies the parameters that are used to compute the edge gradient information and detect the edges.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Edge Polarity specifies the polarity of the edges to be found.

All Edges (0)

(Default) Searches for all edges

Rising Edges (1)

Searches for rising edges

Falling Edges (2)

Searches for falling edges

/images/reference/en-XX/help/370281AG-01/cu32.gif

Kernel Size specifies the size of the edge detection kernel. The default is 3.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Width specifies the number of pixels averaged perpendicular to the search direction to compute the edge profile strength at each point along the search ROI. The default is 3.

/images/reference/en-XX/help/370281AG-01/csgl.gif

Minimum Edge Strength specifies the minimum edge strength (gradient magnitude) required for a detected edge. The default is 10.

/images/reference/en-XX/help/370281AG-01/cenum.gif

Interpolation Type specifies the interpolation method used to locate the edge position.

Choose from the following options:

Zero Order (0)

Rounds to the nearest integral edge location

Bilinear (1)

Uses bilinear interpolation to compute the edge location

Bilinear Fixed (4)

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

/images/reference/en-XX/help/370281AG-01/cenum.gif

Data Processing Method is the method used to process the data extracted for edge detection.

Average (0)

(Default) Averages the data extracted for edge detection

Median (1)

Takes the median of the data extracted for edge detection

/images/reference/en-XX/help/370281AG-01/cbool.gif

Show Search Area determines whether to overlay the ROI on the image.

/images/reference/en-XX/help/370281AG-01/cbool.gif

Show Search Lines determines whether the search lines used to locate the edges are overlaid on the image.

/images/reference/en-XX/help/370281AG-01/cbool.gif

Show Edges Found determines whether the locations of the edges found are overlaid on the result image.

/images/reference/en-XX/help/370281AG-01/cbool.gif

Show Result determines whether the coordinate system found is overlaid on the result image.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Search Area Color specifies the color to use to overlay the search area.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Search Lines Color specifies the color to use to overlay the search lines.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Edge Locations Color specifies the color to use to overlay the edge locations.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Result Color specifies the color to use to overlay the result.

/images/reference/en-XX/help/370281AG-01/cstr.gif

Overlay Group Name specifies the overlay group name for the step overlays.

/images/reference/en-XX/help/370281AG-01/cgenclasstagrefflat.gif

Image is a reference to the image in which you want to search.

/images/reference/en-XX/help/370281AG-01/ccclst.gif

ROI Descriptor is a descriptor that defines the rectangle, rotated rectangle, or other four-side rectangular polygon within which the edge detection is performed.

/images/reference/en-XX/help/370281AG-01/c1di32.gif

Global Rectangle contains the coordinates of the bounding rectangle.

/images/reference/en-XX/help/370281AG-01/c1dcclst.gif

Contours are each of the individual shapes that define an ROI.

/images/reference/en-XX/help/370281AG-01/cenum.gif

ID refers to whether the contour is the external or internal edge of an ROI.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Type is the shape type of the contour.

/images/reference/en-XX/help/370281AG-01/c1di32.gif

Coordinates indicates the relative position of the contour.

/images/reference/en-XX/help/370281AG-01/ccclst.gif

Coordinate System specifies the coordinate system to use.

/images/reference/en-XX/help/370281AG-01/cerrcodeclst.gif

error in (no error) describes the error status before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

/images/reference/en-XX/help/370281AG-01/cbool.gif

status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.

/images/reference/en-XX/help/370281AG-01/ci32.gif

code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.

/images/reference/en-XX/help/370281AG-01/cstr.gif

source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

/images/reference/en-XX/help/370281AG-01/cnclst.gif

Line Fit Options specifies the options that are used to detect the straight edges.

/images/reference/en-XX/help/370281AG-01/ci32.gif

Number of Lines specifies the number of straight edges to find. The default is 1.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Type specifies the method used to find the straight edge. Choose from the following options:

First Edge Rake (0)

(Default) Fits a straight edge on the first points detected using a Rake

Best Edge Rake (1)

Fits a straight edge on the best points detected using a Rake

Hough Edge Rake (2)

Finds the strongest straight edge using all points detected on a Rake

First Edge Projection (3)

Uses the location of the first projected edge as the straight edge

Best Edge Projection (4)

Finds the strongest projected edge location to determine the straight edge

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Min. Score specifies the minimum score of a detected straight edge. The default is 10.

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Max. Score specifies the maximum score of a detected straight edge. The default is 1000.

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Orientation specifies the angle at which the straight edge is expected to be found. The default is 0.

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Angle Range specifies the positive and negative range around the Orientation within which the straight edge is expected to be found. The default is 45.

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Angle Tolerance specifies the expected angular accuracy of the straight edge. The default is 1.

/images/reference/en-XX/help/370281AG-01/cu32.gif

Step Size specifies the gap in pixels between the search lines used with the Rake-based methods. The default is 7.

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Min. SNR (db) specifies the minimum signal to noise ratio (SNR) of the edge points used to fit the straight edge. The default is 0.

/images/reference/en-XX/help/370281AG-01/cdbl.gif

Min. Points (%) specifies the minimum number for points as a percentage of the number of search lines that need to be included in the detected straight edge. The default is 25%.

/images/reference/en-XX/help/370281AG-01/ci32.gif

Hough Iterations specify the number of iterations used in the Hough-based method. The default is 5.

/images/reference/en-XX/help/370281AG-01/igenclasstagrefflat.gif

Image Out is a reference to Image.

/images/reference/en-XX/help/370281AG-01/i1dcclst.gif

Straight Edges contains information about the detected straight edges. If there are no elements in the Straight Edges array, it means that no edges were found.

/images/reference/en-XX/help/370281AG-01/inclst.gif

Point1 (Pixels) is the start point of the detected straight edge in pixel units.

/images/reference/en-XX/help/370281AG-01/inclst.gif

Point2 (Pixels) is the end point of the detected straight edge in pixel units.

/images/reference/en-XX/help/370281AG-01/inclst.gif

Point1 (Real-World) is the start point of the detected straight edge in calibrated units.

/images/reference/en-XX/help/370281AG-01/inclst.gif

Point2 (Real-World) is the end point of the detected straight edge in calibrated units.

/images/reference/en-XX/help/370281AG-01/idbl.gif

Angle (Pixel) is the angle the detected straight edge makes with the axis perpendicular to the search direction.

/images/reference/en-XX/help/370281AG-01/idbl.gif

Angle (Real-World) is the angle the detected straight edge makes with the axis perpendicular to the search direction in calibrated units.

/images/reference/en-XX/help/370281AG-01/idbl.gif

Score is the score of the detected straight edge.

/images/reference/en-XX/help/370281AG-01/idbl.gif

Straightness is the straightness value of the detected straight edge. Straightness is defined as the root mean squared error of the fitted line that represents the detected straight edge. A value of 0 indicates a perfectly straight line.

/images/reference/en-XX/help/370281AG-01/idbl.gif

Average SNR (dB) is the average signal-to-noise ratio along the detected straight edge.

/images/reference/en-XX/help/370281AG-01/ibool.gif

Calibration Valid indicates if the calibration information associated with the edges found along the search line is valid. If the calibration information is invalid for any pixel that is used for edge detection, the Calibration Valid Boolean is FALSE.

/images/reference/en-XX/help/370281AG-01/icclst.gif

Coordinate System (duplicate) is a reference to the coordinate system.

/images/reference/en-XX/help/370281AG-01/ierrcodeclst.gif

error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.

/images/reference/en-XX/help/370281AG-01/ibool.gif

status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.

/images/reference/en-XX/help/370281AG-01/ii32.gif

code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.

/images/reference/en-XX/help/370281AG-01/istr.gif

source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

WAS THIS ARTICLE HELPFUL?

Not Helpful