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PathTurnAngleLocalMaxima


Header: FIL.h
Namespace: fil
Module: FoundationPro

Finds the local maxima of the profile of turn angles of a path.

Applications: Detection of feature points related to object corners.

Syntax

C++
C#
 
void fil::PathTurnAngleLocalMaxima
(
	const fil::Path& inPath,
	fil::TurnAngleDirection::Type inAllowedTurnDirection,
	fil::TurnAnglePrecision::Type inResultPrecision,
	const float inMinTurnAngle,
	const float inMinDistance,
	const float inSmoothingStdDev,
	ftl::Array<float>& outTurnAngleMaximaIndices,
	ftl::Array<fil::Point2D>& outTurnAngleMaximaPoints,
	ftl::Array<float>& outTurnAngleMaximaAngles,
	fil::Path& diagSmoothedPath,
	fil::Profile& diagTurnAngleProfile
)

Parameters

Name Type Range Default Description
Input value
 inPath const Path& Input path
Input value
 inAllowedTurnDirection TurnAngleDirection::Type All Allows to detect only left-turns, only right-turns or both
Input value
 inResultPrecision TurnAnglePrecision::Type Switches between pixel-precise or subpixel-precise detection of the found maxima
Input value
 inMinTurnAngle const float 0.0 - 180.0 30.0f Minimal value of a relevant angle
Input value
 inMinDistance const float 0.0 - 0.0f Minimal distance on the path between two local maxima assuming each path segment has unit length
Input value
 inSmoothingStdDev const float 0.0 - 0.6f Standard deviation of the gaussian smoothing applied to the input path
Output value
 outTurnAngleMaximaIndices Array<float>& Indices of found local maxima
Output value
 outTurnAngleMaximaPoints Array<Point2D>& Found local maxima of turn angle profile of the smoothed input path
Output value
 outTurnAngleMaximaAngles Array<float>& Turn angles of found local maxima
Diagnostic input
 diagSmoothedPath Path& Input path smoothed with gaussian kernel
Diagnostic input
 diagTurnAngleProfile Profile& Profile of turn angles at characteristic points of the smoothed input path

Description

The operation computes the profile of turn angles of a path and finds the local maxima of the profile having value at least inMinTurnAngle. The inAllowedTurnDirection parameter restricts kind of turns taken into consideration (left-turns only, right-turns only or both), while inResultPrecision determines the precision of the resulting maxima points. Found maxima have to be at least inMinDistance from each other (the distance is measured along the input path assuming each path segment has unit length).

Examples

PathTurnAngleLocalMaxima run on the sample path with inAllowedTurnDirection = Right

See Also