NI Vision for LabVIEW

IMAQ Match Feature Points VI

  • Updated2023-02-21
  • 5 minute(s) read
Owning Palette: Feature Correspondence
Requires: NI Vision Development Module

Computes correspondence between feature points.

Examples

IMAQ Match Feature Points

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Feature Points 1 defines the locations of the feature points detected in the First Image.

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X is the x-coordinate of the point.

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Y is the y-coordinate of the point.

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Feature Descriptors 1 defines the descriptors for all the feature points detected in the First Image

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Feature Points 2 defines the locations of the feature points detected in the Second Image.

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X is the x-coordinate of the point.

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Y is the y-coordinate of the point.

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Feature Descriptors 2 defines the descriptors for all the detected feature points in the Second Image

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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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Max Acceptable Distance specifies the maximum difference between the two feature point descriptors above which the points will not be considered as a match.

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Error Threshold is the allowed error tolerance in pixels during the matching process.

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Match Locations returns the coordinates of the all the feature points that match between the two images.

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Image 1

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X is the x-coordinate of the point.

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Y is the y-coordinate of the point.

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Image2

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X is the x-coordinate of the point.

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Y is the y-coordinate of the point.

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Match Scores returns the match scores of all the feature points that are matches between the two images

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Homography Matrix returns the homography matrix between the two images

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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.

Examples

Refer to the following for an example that uses this VI.

  • LabVIEW\examples\Vision\Feature Correspondence\Feature Matching.vi