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FitPathToRidges_Direct

Header:	FIL.h
Namespace:	fil
Module:	MetrologyPro

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

Applications: Tracing of a thin line, whose rough location and shape is known beforehand.

Syntax

void fil::FitPathToRidges_Direct
(
	const fil::Image& inImage,
	const fil::PathFittingField& inFittingField,
	ftl::Optional<const fil::CoordinateSystem2D&> inFittingFieldAlignment,
	ftl::Optional<float> inScanStep,
	int inScanWidth,
	const fil::SamplingParams& inSamplingParams,
	const fil::RidgeScanParams& inRidgeScanParams,
	fil::Selection::Type inRidgeSelection,
	ftl::Optional<const fil::LocalBlindness&> inLocalBlindness,
	ftl::Optional<int> inMaxInterpolationLength,
	ftl::Optional<float> inMaxDeviationDelta,
	float inMaxIncompleteness,
	ftl::Conditional<fil::Path>& outPath,
	ftl::Optional<ftl::Array<ftl::Conditional<fil::Ridge1D>>&> outRidges = ftl::NIL,
	ftl::Optional<ftl::Conditional<fil::Profile>&> outDeviationProfile = ftl::NIL,
	ftl::Optional<fil::PathFittingField&> outAlignedFittingField = ftl::NIL,
	ftl::Optional<ftl::Array<fil::Profile>&> outBrightnessProfiles = ftl::NIL,
	ftl::Optional<ftl::Array<fil::Profile>&> outResponseProfiles = ftl::NIL,
	ftl::Array<fil::Segment2D>& diagScanSegments,
	ftl::Array<fil::Rectangle2D>& diagSamplingAreas
)

Parameters

Name	Type	Range	Default	Description
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)
inSamplingParams	const SamplingParams&			Parameters controlling the sampling process
inRidgeScanParams	const RidgeScanParams&		RidgeScanParams ( ProfileInterpolation: Quadratic4 SmoothingStdDev: 0.6f RidgeWidth: 5 RidgeMargin: 2 MinMagnitude: 5.0f RidgePolarity: Dark )	Parameters controlling the ridge extraction process
inRidgeSelection	Selection::Type			Selection mode of ridges
inLocalBlindness	Optional<const LocalBlindness&>		NIL	Defines conditions in which weaker ridges can be detected in the vicinity of stronger ridges
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 ridge points not found
outPath	Conditional<Path>&			Fitted path or nothing if the fitting failed
outRidges	Optional<Array<Conditional<Ridge1D>>&>		NIL	Found ridges
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
outBrightnessProfiles	Optional<Array<Profile>&>		NIL	Extracted image profiles
outResponseProfiles	Optional<Array<Profile>&>		NIL	Profiles of the ridge operator response
diagScanSegments	Array<Segment2D>&			Segments along which the scans were run
diagSamplingAreas	Array<Rectangle2D>&			Areas from which the input image is sampled

Optional Outputs

The computation of following outputs can be switched off by passing value ftl::NIL to these parameters: outRidges, outDeviationProfile, outAlignedFittingField, outBrightnessProfiles, outResponseProfiles.

Description

The operation tries to fit a given path to ridges present in the inImage image. Internally, it performs a series of scans with the ScanSingleRidge_Direct filter along a number of specific scan segments which length is always equal to the inFittingField width and cannot be less than 4. 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 inRidgeScanParams.RidgePolarity to detect a particular ridge type, and only that type.
Adjust inRidgeScanParams.RidgeWidth to the expected thickness of the ridge (in pixels).
If no or too few ridge points are found, try decreasing inRidgeScanParams.MinMagnitude.
If some of the scans may fail, set the inMaxIncompleteness input accordingly.
Use the outRidges outputs to visualize the scanning results.

Examples

Fitting a path to the walls of a plastic capsule
(inRidgeScanParams.RidgePolarity = Dark, inRidgeScanParams.RidgeWidth = 6, inRidgeScanParams.RidgeOperator = ArithmeticMean).

Remarks

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

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.