IMAQ Find Pattern 4 VI

NI Vision 2019 for LabVIEW Help

Edition Date: March 2019

Part Number: 370281AG-01

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Owning Palette: Find Patterns
Requires: NI Vision Development Module

Searches for a template image in a rectangular search area of the image.

Supported Image Types

8-bit unsigned grayscale

IMAQ Find Pattern 4

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Template is a reference to the image to locate during the match process. The template image is the image obtained from the output of the IMAQ Learn Pattern 5 VI. If the template has not been learned, this VI first goes through the learning process.

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Image is a reference to the source image.

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Search Rect specifies a rectangular search area in an image. The Left, Top, Right, and Bottom coordinates describe a non-rotated rectangle. The Rotation specifies the rotation angle of the rectangle around its center.

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Left is the x-coordinate of the upper left corner of the rectangle.

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Top is the y-coordinate of the upper left corner of the rectangle.

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Right is the x-coordinate of the bottom right corner of the rectangle.

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Bottom is the y-coordinate of the bottom right corner of the rectangle.

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Rotation specifies the rotation angle in degrees of the rectangle with its center as point of rotation. If the rotation angle does not equal zero, the Left, Top, Right, and Bottom coordinates are not the actual coordinates of the upper left and bottom right corner of the rectangle, but their position if the rotation angle equals zero.

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Coordinate System specifies the coordinate system to which the Rectangle is linked. If the Coordinate System input is used (connected), the location of the intensity measurement is shifted and rotated by the difference between the reference position of the coordinate system and its new location.

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Reference System is a cluster containing the following elements.

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Origin is a point cluster that specifies the origin of the base-reference coordinate system.

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X is the x-coordinate of the center of the pattern.

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Y is the y-coordinate of the center of the pattern.

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Angle (deg) is the angle the base-reference coordinate system makes with the image coordinate system.

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Axis Reference is defined as Direct or Indirect. Refer to Axis Type for more information.

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Measurement System is a cluster containing the following elements.

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Origin is a point cluster that specifies the origin of the base-reference coordinate system.

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X is the x-coordinate of the center of the pattern.

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Y is the y-coordinate of the center of the pattern.

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Angle (deg) is the angle the base-reference coordinate system makes with the image coordinate system.

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Axis Reference is defined as Direct or Indirect. Refer to Axis Type for more information.

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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.

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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.

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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.

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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.

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Settings is a cluster defining the parameters of the template location algorithm and the information that is overlaid on the result image.

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Algorithm specifies the pattern matching algorithm to use to find the template information. All learns the template using all of the algorithms.

Refer to the NI Vision Concepts Help for in-depth information about each algorithm.

All (0)

Uses all of the algorithms, one after the other.

Low Discrepancy Sampling (1)

Uses a low discrepancy sampling algorithm. This algorithm extracts the most significant information to represent an image. If your template contains large regions of similar grayscale information, a wide aspect ratio, or is very small, use one of the pyramidal matching algorithms instead.

Grayscale Value Pyramid (2)

Uses a grayscale value pyramid algorithm. This algorithm uses normalized gray values as features, and is useful when the template does not contain structured information, but has intricate textures for dense edges.

Gradients Pyramid (3)

Uses a graident pyramid algorithm. This algorithm uses filtered edge pixels as features. This algorithm is more resistant to occlusion and intensity changes compared to the Grayscale Value Pyramid, and is often being faster because of a smaller amount of data. However, the strength and reliability of edges reduces at very low resolutions this method requires the user to sometimes work at higher resolutions compared to the gray value method.

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Number of Matches Requested is the number of valid matches expected.

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Minimum Match Score is the smallest score a match must have to be considered valid.

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SubPixel Accuracy determines whether the match results should be returned with subpixel accuracy.

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Rotation Angle Ranges is an array of angle ranges where each range specifies how much you expect the template pattern to rotate in the image. Each range is specified by a start angle and an end angle, both of which are expressed in degrees.

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Show Search Area specifies whether the centers and bounding rectangles of the patterns found are overlaid on the result image.

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Show Result Show Result specifies whether the centers and bounding boxes of the patterns found are overlaid on the result image.

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Elapsed time (ms) returns the duration of the search, in milliseconds.

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Matches is an array of match clusters. Matches returns the following elements:

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Position is a point-coordinate cluster corresponding to the center of the template.

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Angle is the rotation angle of the template in the source image at the current match location.

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Scale is the change in percentage size of the matched template from the original template. This parameter is not used for pattern matching, and is always set to 1.

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Score ranks the match results on a scale of 0 to 1,000, where 0 equals no match and 1,000 equals a perfect match.

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Bounding Box is an array of points that define the boundary of the template pattern in the image. You can connect this array directly to the IMAQ Overlay Multiple Lines 2 VI to overlay the location of a match on your image.

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Image Out is a reference to the destination image. The search area and/or the result of the measurement may be overlaid on the image according to the settings.

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Number of Matches is the number of template matches found in the inspection image based on the input settings.

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

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Reference System is a cluster containing the following elements.

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Origin is a point cluster that specifies the origin of the base-reference coordinate system.

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

X is the x-coordinate of the center of the pattern.

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

Y is the y-coordinate of the center of the pattern.

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Angle (deg) is the angle the base-reference coordinate system makes with the image coordinate system.

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Axis Reference is defined as Direct or Indirect. Refer to Axis Type for more information.

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

Measurement System is a cluster containing the following elements.

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

Origin is a point cluster that specifies the origin of the base-reference coordinate system.

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

X is the x-coordinate of the center of the pattern.

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

Y is the y-coordinate of the center of the pattern.

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

Angle (deg) is the angle the base-reference coordinate system makes with the image coordinate system.

/images/reference/en-XX/help/370281AG-01/iu32.gif

Axis Reference is defined as Direct or Indirect. Refer to Axis Type for more information.

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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.

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

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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.

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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.

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