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DetectPaths


Header: FIL.h
Namespace: fil
Module: FoundationBasic

Finds a specified shape in an image using Hough Transform.

Applications: This is an old algorithm for template matching. Quite slow.

Syntax

C++
C#
 
void fil::DetectPaths
(
	const fil::Image& inImage,
	ftl::Optional<const fil::Region&> inRoi,
	const fil::Path& inPath,
	float inMinScore,
	float inEdgeThreshold,
	ftl::Array<fil::Path>& outPaths,
	ftl::Array<float>& outScores,
	fil::Image& diagGradientMagnitudeImage,
	fil::Image& diagScoreImage
)

Parameters

Name Type Range Default Description
Input value inImage const Image& Input image
Input value inRoi Optional<const Region&> NIL Input region of interest
Input value inPath const Path& Input path
Input value inMinScore float 0.0 - 20.0f Minimum matching score
Input value inEdgeThreshold float 10.0f Minimum accepted edge magnitude
Output value outPaths Array<Path>& Output paths
Output value outScores Array<float>& Output scores
Diagnostic input diagGradientMagnitudeImage Image& Visualized gradients magnitude of an input image
Diagnostic input diagScoreImage Image& Calculated score for each pixel of an input image

Description

The operation detects paths in the inImage using the Generalized Hough Transform approach. The output array is ordered from best matching to worst matching results.

Examples

A sample path (scaled for convenience).

DetectPaths performed on the sample images with inMinScore = 0.7.

Remarks

DetectPaths is not scale- or rotation-invariant (slightly scaled or rotated paths are, however, detected properly).

Long inPaths cause long computation time.

Errors

List of possible exceptions:

Error type Description
DomainError Degenerate path in DetectPaths.

See Also

  • DetectLines – Finds lines in an image using Hough Transform.
  • DetectSegments – Finds segments in an image using Hough Transform.