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ScanSingleEdge

Locates the strongest transition between dark and bright pixels along a given path.

Name	Type	Range	Description
inImage	Image		Input image
inScanPath	Path		Path along which the scan is performed
inScanPathAlignment	CoordinateSystem2D *		Adjusts the scan path to the position of the inspected object
inScanWidth	Integer	1 -	Width of the scan field in pixels
inImageInterpolation	InterpolationMethod		Interpolation method used for extraction of image pixels
inEdgeScanParams	EdgeScanParams		Parameters controlling the edge extraction process
inEdgeSelection	Selection		If many edge points are possible, defines which one is selected
inLocalBlindness	LocalBlindness *		Defines conditions in which weaker edges can be detected in the vicinity of stronger edges
outEdge	Edge1D ?		Found edge
outAlignedScanPath	Path		Path along which the scan is performed; in the image coordinate system
diagBrightnessProfile	Profile		Extracted image profile
diagResponseProfile	Profile		Profile of the edge (derivative) operator response
diagSamplingPoints	Path Array		Array of paths each one containing the sampling points that contributed to a single value of the extracted profile

Applications

Very fast detection of an object (e.g. horizontal displacement of a bottle) and simple measurements (e.g. liquid level in a bottle).

Description

The operation scans the image along inScanPath and locates the strongest edge perpendicular to the path. If the strongest edge is weaker than inEdgeScanParams.minMagnitude then the outputs are set to NIL.

The optional parameter inScanPathAlignment defines a transform to be performed on the inScanPath so that the actual scan path (outAlignedScanPath) is adjusted to the position of the object, typically detected by one of Template Matching filters.

Hints

Connect an input image to the inImage input.
Create inScanPath which is more or less perpendicular to the edge you want to detect. It should be long enough to anticipate all possible edge locations.
Define inEdgeScanParams.EdgeTransition to detect a particular edge type, and only that type.
Use a local coordinate system connected to inScanPathAlignment to automatically adjust the measurement to variable object position (optional).
If the noise level is high, try increasing inScanWidth and/or inEdgeScanParams.SmoothingStdDev.
If no edge is found, try decreasing inEdgeScanParams.MinMagnitude. Verify this with the values on the diagResponseProfile output.
If consecutive edges are closer than 6 pixels apart, change inEdgeScanParams.ProfileInterpolation to Quadratic3.

Examples

Description of usage of this filter can be found in examples and tutorial: Bottle Inspection, Cap, Cap (Advanced), Bottle Inspector Part 2: Measuring Liquid Level, Bottle Inspector Part 3: Foam Detection.

ScanSingleEdge locates the strongest edge across inScanPath.

Remarks

For more information about local coordinate systems please refer to the following article.

This filter is a part of the 1D Edge Detection toolset. For a comprehensive introduction to this technique please refer to 1D Edge Detection and 1D Edge Detection - Subpixel Precision chapters of our Machine Vision Guide.

Complexity Level

This filter is available on Basic Complexity Level.

Filter Group

This filter is member of ScanEdges filter group.