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AvsFilter_FitPathToEdges

This is Filter Equivalent. This function may be present in generated code, but should not be used in hand-written code. CreatePathFittingMap and FitPathToEdges should be used instead.

Performs a series of 1D edge detections and creates a path from the detected points.

Syntax

void avs::AvsFilter_FitPathToEdges
(
	FitPathToEdgesState& ioState,
	const avl::Image& inImage,
	const avl::PathFittingField& inFittingField,
	atl::Optional<const avl::CoordinateSystem2D&> inFittingFieldAlignment,
	atl::Optional<float> inScanStep,
	int inScanWidth,
	const avl::InterpolationMethod::Type inImageInterpolation,
	const avl::EdgeScanParams& inEdgeScanParams,
	avl::Selection::Type inEdgeSelection,
	atl::Optional<const avl::LocalBlindness&> inLocalBlindness,
	atl::Optional<int> inMaxInterpolationLength,
	atl::Optional<float> inMaxDeviationDelta,
	float inMaxIncompleteness,
	atl::Conditional<avl::Path>& outPath,
	atl::Optional<atl::Array<atl::Conditional<avl::Edge1D> >&> outEdges = atl::NIL,
	atl::Optional<atl::Conditional<avl::Profile>&> outDeviationProfile = atl::NIL,
	atl::Optional<avl::PathFittingField&> outAlignedFittingField = atl::NIL,
	atl::Array<avl::Segment2D>& diagScanSegments,
	atl::Array<avl::Rectangle2D>& diagSamplingAreas,
	atl::Array<avl::Profile>& diagBrightnessProfiles,
	atl::Array<avl::Profile>& diagResponseProfiles
)

Parameters

Name	Type	Range	Default	Description
ioState	FitPathToEdgesState&			Object used to maintain state of the function.
inImage	const Image&			Image to fit the path to
inFittingField	const PathFittingField&			Path fitting field
inFittingFieldAlignment	Optional<const CoordinateSystem2D&>		NIL	Adjusts the fitting field to the position of the inspected object
inScanStep	Optional<float>	0.0 -	5.0f	Optional implicit conversion of the input path to an equidistant one
inScanWidth	int	1 -	5	The width of each scan field (in pixels)
inImageInterpolation	const InterpolationMethod::Type		Bilinear	Interpolation method used for extraction of image pixel values
inEdgeScanParams	const EdgeScanParams&		EdgeScanParams ( ProfileInterpolation: Quadratic4 SmoothingStdDev: 0.6f MinMagnitude: 5.0f EdgeTransition: BrightToDark )	Parameters controlling the edge extraction process
inEdgeSelection	Selection::Type			Selection mode of edges
inLocalBlindness	Optional<const LocalBlindness&>		NIL	Defines conditions in which weaker edges can be detected in the vicinity of stronger edges
inMaxInterpolationLength	Optional<int>	0 -	1	Maximal number of consecutive points not found
inMaxDeviationDelta	Optional<float>	0.0 -	NIL	Maximal difference between deviations of consecutive path points
inMaxIncompleteness	float	0.0 - 0.999	0.1f	Maximal fraction of edge points not found
outPath	Conditional<Path>&			Fitted path or nothing if the fitting failed
outEdges	Optional<Array<Conditional<Edge1D> >&>		NIL	Found edges
outDeviationProfile	Optional<Conditional<Profile>&>		NIL	Profile of distances between the actual path points and the corresponding reference path points
outAlignedFittingField	Optional<PathFittingField&>		NIL	Fitting field used; in the image coordinate system
diagScanSegments	Array<Segment2D>&			Segments along which the scans were run
diagSamplingAreas	Array<Rectangle2D>&			Areas from which the input image is sampled
diagBrightnessProfiles	Array<Profile>&			Extracted image profiles
diagResponseProfiles	Array<Profile>&			Profiles of the edge (derivative) operator response

Description

The operation tries to fit a given path to edges present in the inImage image. Internally, it performs a series of scans with the ScanSingleEdge filter along a number of specific scan segments which length is always equal to the inFittingField width. The found points are then used to determine the actual position of the path in the image. Only inMaxIncompleteness fraction of these scans may fail. If the fitting according to the given parameters is not possible, outPath is set to Nil.

There are also another parameters that control the path fitting process. The inMaxDeviationDelta parameter defines the maximal allowed difference between deviations of consecutive points from the input path points. If some of the scans fail or if some of found points are classified to be wrong according to another control parameters, output path points corresponding to them are interpolated depending on points in their nearest vicinity. No more than inMaxInterpolationLength consecutive points can be interpolated. The exception to this behavior are points which were not found on both ends of the input path. Those are not part of the result at all.

Hints

Connect an input image to the inImage input.
Define inEdgeScanParams.EdgeTransition to detect a particular edge type, and only that type.
If no or too few edge points are found, try decreasing inEdgeScanParams.MinMagnitude.
If some of the scans may fail, set the inMaxIncompleteness input accordingly.
Use the outEdges outputs to visualize the scanning results.

Examples

Fitting a path to the edges of a plastic capsule
(inEdgeSelection = First, inEdgeScanParams.EdgeTransition = BrightToDark).

Remarks

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

This filter is a part of the Shape Fitting toolset. To read more about this technique, one can refer to the Shape Fitting chapter of our Machine Vision Guide

Hardware Acceleration

This operation supports automatic parallelization for multicore and multiprocessor systems.