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# FitPathToRidges

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

C++
C#

void avl::FitPathToRidges
(
const avl::Image& inImage,
const avl::PathFittingMap& inFittingMap,
const RidgeScanParams& inRidgeScanParams,
avl::Selection::Type inRidgeSelection,
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::Ridge1D> >&> outRidges = atl::NIL,
atl::Optional<atl::Conditional<avl::Profile>&> outDeviationProfile = atl::NIL,
atl::Array<avl::Profile>& diagBrightnessProfiles,
atl::Array<avl::Profile>& diagResponseProfiles
)


### Parameters

Name Type Range Default Description
inImage const Image& Image to fit the path to
inFittingMap const PathFittingMap& Input fitting map
inRidgeScanParams const RidgeScanParams& Parameters controlling the ridge extraction process
inRidgeSelection Selection::Type Selection::​Best 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 - 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 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
diagBrightnessProfiles Array<Profile>& Extracted image profiles
diagResponseProfiles Array<Profile>& Profiles of the ridge operator response

### Optional Outputs

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

### 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 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 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.