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ScanSingleEdge

Header:	AVL.h
Namespace:	avl
Module:	MetrologyBasic

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

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

Syntax

void avl::ScanSingleEdge
(
	const avl::Image& inImage,
	const avl::ScanMap& inScanMap,
	const avl::EdgeScanParams& inEdgeScanParams,
	avl::Selection::Type inEdgeSelection,
	atl::Optional<const avl::LocalBlindness&> inLocalBlindness,
	atl::Conditional<avl::Edge1D>& outEdge,
	atl::Optional<avl::Profile&> outBrightnessProfile = atl::NIL,
	atl::Optional<avl::Profile&> outResponseProfile = atl::NIL
)

Parameters

Name	Type	Default	Description
inImage	const Image&		Input image
inScanMap	const ScanMap&		Data precomputed with CreateScanMap
inEdgeScanParams	const EdgeScanParams&	EdgeScanParams ( ProfileInterpolation: Quadratic4 SmoothingStdDev: 0.6f MinMagnitude: 5.0f EdgeTransition: BrightToDark )	Parameters controlling the edge extraction process
inEdgeSelection	Selection::Type	Selection::Best	Selection mode of the resulting edge
inLocalBlindness	Optional<const LocalBlindness&>	NIL	Defines conditions in which weaker edges can be detected in the vicinity of stronger edges
outEdge	Conditional<Edge1D>&		Found edge
outBrightnessProfile	Optional<Profile&>	NIL	Extracted image profile
outResponseProfile	Optional<Profile&>	NIL	Profile of the edge (derivative) operator response

Optional Outputs

The computation of following outputs can be switched off by passing value atl::NIL to these parameters: outBrightnessProfile, outResponseProfile.

Description

The operation scans the image using inScanMap previously generated from a scan path 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.

Hints

Define inEdgeScanParams.EdgeTransition to detect a particular edge type, and only that type.
If no edge is found, try decreasing inEdgeScanParams.MinMagnitude. Verify this with the values on the outResponseProfile output.
If consecutive edges are closer than 6 pixels apart, change inEdgeScanParams.ProfileInterpolation to Quadratic3.

Examples

ScanSingleEdge locates the strongest edge using a scan map representing the scan path above.

Remarks

Read more about Local Coordinate Systems in Machine Vision Guide: Local Coordinate Systems.

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.