You are here: Start » Function Reference » Shape Fitting » FitArcToStripe

FitArcToStripe

Performs a series of 1D stripe detections and finds an arc that best matches the detected points.

Syntax

void avl::FitArcToStripe
(
	const avl::Image& inImage,
	const avl::ArcFittingMap& inFittingMap,
	const StripeScanParams& inStripeScanParams,
	avl::Selection::Type inStripeSelection,
	atl::Optional<const avl::LocalBlindness&> inLocalBlindness,
	float inMaxIncompleteness,
	avl::CircleFittingMethod::Type inFittingMethod,
	atl::Optional<avl::MEstimator::Type> inOutlierSuppression,
	atl::Conditional<avl::Arc2D>& outArc,
	atl::Conditional<avl::Arc2D>& outInnerArc,
	atl::Conditional<avl::Arc2D>& outOuterArc,
	atl::Array<atl::Conditional<avl::Stripe1D> >& outStripes,
	atl::Optional<atl::Array<avl::Point2D>&> outStripePoints = atl::NIL,
	atl::Optional<atl::Conditional<avl::Profile>&> outDeviationProfile = atl::NIL,
	atl::Array<avl::Profile>& diagBrightnessProfiles,
	atl::Array<avl::Profile>& diagResponseProfiles
)

void FitArcToStripe
(
	Image inImage,
	ArcFittingMap inFittingMap,
	StripeScanParams inStripeScanParams,
	Selection inStripeSelection,
	LocalBlindness? inLocalBlindness,
	float inMaxIncompleteness,
	CircleFittingMethod inFittingMethod,
	MEstimator? inOutlierSuppression,
	out Arc2D? outArc,
	out Arc2D? outInnerArc,
	out Arc2D? outOuterArc,
	out Stripe1D?[] outStripes,
	out Point2D[] outStripePoints,
	out Profile? outDeviationProfile,
	out Profile[] diagBrightnessProfiles,
	out Profile[] diagResponseProfiles
)

Parameters

Name	Type	Range	Default	Description
inImage	const Image&			Input image to fit arc to
inFittingMap	const ArcFittingMap&			Input fitting map
inStripeScanParams	const StripeScanParams&			Parameters controlling the stripe extraction process
inStripeSelection	Selection::Type		Selection::Best	Selection mode of stripe
inLocalBlindness	Optional<const LocalBlindness&>		NIL	Defines conditions in which weaker edges can be detected in the vicinity of stronger edges
inMaxIncompleteness	float	0.0 - 0.999	0.1f	Maximal fraction of stripe points not found
inFittingMethod	CircleFittingMethod::Type		AlgebraicTaubin	Method used to fit an arc
inOutlierSuppression	Optional<MEstimator::Type>		NIL	Selects a method for ignoring incorrectly detected points
outArc	Conditional<Arc2D>&			Fitted arc in the middle of found stripe
outInnerArc	Conditional<Arc2D>&			Fitted inner arc
outOuterArc	Conditional<Arc2D>&			Fitted outer arc
outStripes	Array<Conditional<Stripe1D> >&			Found stripes
outStripePoints	Optional<Array<Point2D>&>		NIL	Extracted points of middle arc of an image stripe
outDeviationProfile	Optional<Conditional<Profile>&>		NIL	Profile of distances between the actual arc points and the corresponding reference arc points
diagBrightnessProfiles	Array<Profile>&			Extracted image profiles
diagResponseProfiles	Array<Profile>&			Profiles of the edge (derivative) operator response

Description

The operation tries to fit a given arc to stripe present in the inImage image. Internally, it performs a series of scans with the ScanSingleStripe filter using inFittingMap previously generated from the object being fitted. The found points are then used to determine the actual position of the arc in the image. Only inMaxIncompleteness fraction of these scans may fail. If the fitting according to the given parameters is not possible, outArc is set to Nil.

Hints

Connect an input image to the inImage input.
Define inStripeScanParams.StripePolarity to detect a particular stripe type, and only that type.
Adjust inStripeScanParams.MinStripeWidth and inStripeScanParams.MaxStripeWidth to the expected thickness of the stripe (in pixels).
If no or too few stripe points are found, try decreasing inStripeScanParams.MinMagnitude.
If some of the scans may fail, set the inMaxIncompleteness input accordingly.
If some of the scans may produce false results, try different values of the inOutlierSuppression input.
Use the outStripePoints outputs to visualize the scanning results.

Examples

Fitting an arc to the dark stripe formed on one side of a hole
(inStripeScanParams.Polarity = Dark).

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.