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ScanMultipleRidges


Header:AVL.h
Namespace:avl

Locates multiple dark or bright pixel peaks along a given path.

Syntax

C++
C#
 
void avl::ScanMultipleRidges
(
	const avl::Image& inImage,
	const ScanMap& inScanMap,
	const RidgeScanParams& inRidgeScanParams,
	float inMinDistance,
	atl::Optional<float> inMaxDistance,
	atl::Optional<const avl::LocalBlindness&> inLocalBlindness,
	atl::Array<avl::Ridge1D>& outRidges,
	atl::Array<avl::Gap1D>& outGaps,
	avl::Profile& diagBrightnessProfile,
	avl::Profile& diagResponseProfile
)

Parameters

Name Type Range Default Description
inImage const Image& Input image
inScanMap const ScanMap& Data precomputed with CreateScanMap
inRidgeScanParams const RidgeScanParams& Parameters controlling the ridge extraction process
inMinDistance float 0.0 - 0.0f Minimal distance between consecutive ridges
inMaxDistance Optional<float> 0.0 - NIL Maximal distance between consecutive ridges
inLocalBlindness Optional<const LocalBlindness&> NIL Defines conditions in which weaker ridges can be detected in the vicinity of stronger ridges
outRidges Array<Ridge1D>& Found ridges
outGaps Array<Gap1D>& Gaps between consecutive ridges
diagBrightnessProfile Profile& Extracted image profile
diagResponseProfile Profile& Profile of the ridge operator response

Description

The operation scans the image using inScanMap previously generated from a scan path and detects ridges. Depending on the inRidgeScanParams.ridgePolarity parameter, dark, bright or both ridges will be taken into account.

When the number of ridges to be measured is known, one can use the ScanExactlyNRidges filter.

Note that in case of a scan path which is closed, the parameters controlling the distances between consecutive found objects do not control the distance between the first and the last of the found objects (counting from the beginning of the scan path).

Hints

  • Define inRidgeScanParams.RidgePolarity to detect a particular ridge type, and only that type.
  • If too few ridges are found, try decreasing inRidgeScanParams.MinMagnitude. Verify this with the values on the diagResponseProfile output.
  • If consecutive ridges are very close to each other, change inRidgeScanParams.ProfileInterpolation to Quadratic3.
  • Adjust inMinDistance (in pixels) to filter out false ridges that appear in proximity to other ridges.

Examples

ScanMultipleRidges locates the ridges using a scan map representing the scan path above.

Remarks

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

This filter is a part of the 1D Edge Detection toolset. For a comprehensive introduction to this technique please refer to 1D Edge Detection and 1D Edge Detection - Subpixel Precision chapters of our Machine Vision Guide.

See Also

  • CreateScanMap – Precomputes a data object that is required for fast 1D edge detection.
  • ScanSingleRidge – Locates the strongest dark or bright pixel peak along a given path.
  • ScanExactlyNRidges – Locates a specified number of the strongest dark or bright pixel peak along a given path.