IMAQ Setup Match Contour Pattern VI

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Updated2023-02-21
7 minute(s) read

Owning Palette: Contour Analysis
Requires: NI Vision Development Module

Sets parameters that are used during the matching process.

IMAQ Setup Match Contour Pattern

Curve Extraction is a cluster containing information about how curves are extracted from the image. For more information, see Contour Analysis Concepts.

Extraction Mode specifies how the VI identifies curves in the image. Choose from the following options:

Normal (0)	(Default) Select Normal if you want the VI to make no assumptions about the uniformity of objects in the image or the image background.
Uniform Regions (1)	Select Uniform Regions if you want the VI to assume that either the objects in the image or the image background consist of uniform pixel values. This allows the VI to more accurately calculate the external curves of the objects.

Edge Threshold specifies the minimum contrast a seed point must have for it to begin a curve. Valid values range from 1 to 255. The default value is 75.

Edge Filter Size specifies the width of the edge filter that the VI uses to identify curves in the image. The following options are available:

Fine (0)	Sets the Edge Filter Size to fine.
Normal (1)	(Default) Sets the Edge Filter Size to normal.
Contour Tracing (2)	Sets the Edge Filter Size to contour tracing, which provides the best results for contour extraction but increases the time required to process the image.

Min Length specifies the length, in pixels, of the smallest curve that you want the VI to identify. The VI ignores any curves that have a length less than this value. The default value is 25.

Search Step Size specifies the distance, in the y direction, between the image rows that the algorithm inspects for curve seed points. Valid values range from 1 to 255. The default value is 15.

Max Endpoint Gap specifies the maximum gap, in pixels, between the endpoints of a curve that the VI identifies as a closed curve. If the gap is larger than this value, the VI identifies the curve as an open curve. The default value is 10.

Subpixel specifies whether to detect curve points with subpixel accuracy. The default is FALSE.

Match Mode is a cluster identifying the conditions under which you want the VI to find template matches.

	Rotation When enabled, the VI searches for occurrences of the template in the inspection image, allowing for template matches to be rotated.
	Scale When enabled, the VI searches for occurrences of the template in the inspection image regardless of whether possible matches are of a different size in the inspection image. The default scale range is 75% to 125%.
	Occlusion specifies whether or not to search for occluded versions of the shape.

Subpixel Accuracy determines whether to return the match results with subpixel accuracy. The default is FALSE. If Match Feature Mode is set to color, the VI ignores Subpixel Accuracy.

Range Settings is an array of the acceptable ranges for each Match Constraints option. To decrease the search time, limit the range of these constraints as much as possible.

Match Constraints specifies the match option whose values you want to constrain by the given range. The following options are available:

Rotation Angle (degrees) (0)	Set a range for this option to specify the angles at which you expect the VI to find template matches in the inspection image. The VI ignores this range if the Rotation is not enabled.
Scale Factor (%) (1)	Set a range for this option to specify the sizes at which you expect the VI to find template matches in the inspection image. The size is expressed as the following percentage: the size of the match divided by size of the template image, multiplied by 100. The VI ignores this range if the Scale is not enabled.
Occlusion (%) (2)	Set a range for this option to specify the amount of occlusion you expect for a match in the inspection image. NI Vision can accurately detect matches that have up to 50% occlusion. The VI ignores this range if the Occlusion is not enabled.

Min is the minimum value of the range for a given Match Constraint.

Max is the maximum value of the range for a given Match Constraint.

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.

	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.
	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.
	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.

Use Learn Curve Extraction specifies whether to use the Contour Learn Options parameters from the IMAQ Setup Learn Contour Pattern VI to extract the target contours during the match phase.

Match Contour Pattern Setup Data is a string that contains information about the setup parameters for the matching phase.

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.

	status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
	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.
	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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IMAQ Setup Match Contour Pattern VI

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