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FitPathToEdges

Header:	FIL.h
Namespace:	fil
Module:	MetrologyPro

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

Applications: Tracing of an object contour, whose rough location and shape is known beforehand.

Syntax

void fil::FitPathToEdges
(
	const fil::Image& inImage,
	const PathFittingMap& inFittingMap,
	const EdgeScanParams& inEdgeScanParams,
	fil::Selection::Type inEdgeSelection,
	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::Edge1D>>&> outEdges = ftl::NIL,
	ftl::Optional<ftl::Conditional<fil::Profile>&> outDeviationProfile = ftl::NIL,
	ftl::Optional<ftl::Array<fil::Profile>&> outBrightnessProfiles = ftl::NIL,
	ftl::Optional<ftl::Array<fil::Profile>&> outResponseProfiles = ftl::NIL
)

Parameters

Name	Type	Range	Default	Description
inImage	const Image&			Image to fit the path to
inFittingMap	const PathFittingMap&			Input fitting map
inEdgeScanParams	const EdgeScanParams&			Parameters controlling the edge extraction process
inEdgeSelection	Selection::Type		Selection::Best	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 -	NIL	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
outBrightnessProfiles	Optional<Array<Profile>&>		NIL	Extracted image profiles
outResponseProfiles	Optional<Array<Profile>&>		NIL	Profiles of the edge (derivative) operator response

Optional Outputs

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

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 using inFittingMap previously generated from the object being fitted. 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

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.