MeasureEdgeDistance

Syntax

Definition:

HRESULT MeasureEdgeDistance(
    HRESULT                     hrPrev,
    ITcVnImage*                 ipSrcImage,
    float&                      fAvgDistance,
    TcVnPoint2_REAL&            aStartPoint,
    TcVnPoint2_REAL&            aEndPoint,
    ETcVnEdgeDirection          eEdgeDirection,
    float                       fMinStrength,
    ULONG                       nSearchLines,
    float                       fSearchLineDist = 1,
    ULONG                       nMaxThickness = 10,
    bool                        bInvertSearchDirection = false,
    float                       fSearchGap = 0,
    ULONG                       nSubpixelsIterations = 10,
    float                       fApproxPrecision = 0.001f,
    ETcVnEdgeDetectionAlgorithm eAlgorithm = EDA_INTERPOLATION,
    ITcVnContainer**            pipEdgePoints1 = nullptr,
    ITcVnContainer**            pipEdgePoints2 = nullptr,
    ITcVnContainer**            pipDistances = nullptr
)

Parameters

Name	Type	Default	Description
hrPrev	HRESULT		HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)
ipSrcImage	ITcVnImage*		Source image (1 channel)
fAvgDistance	float&		Returns the average distance between the detected edges
aStartPoint	TcVnPoint2_REAL&		Position from which to start the search process (in the direction of aEndPoint)
aEndPoint	TcVnPoint2_REAL&		Position where the search process ends
eEdgeDirection	ETcVnEdgeDirection		Specification of the edge direction from aStartPoint to aEndPoint to search for
fMinStrength	float		Specification of the minimum strength (intensity difference) of the edge to search for
nSearchLines	ULONG		Width of the search window, i.e. the number of search lines (1, 3, 5, 7, ...), centered around the line specified by aStartPoint and aEndPoint
fSearchLineDist	float	1	Distance between the search lines in pixels (> 0)
nMaxThickness	ULONG	10	Specification of the maximum thickness of the edge to search for, which means fMinStrength must be reached within nMaxThickness pixels
bInvertSearchDirection	bool	false	If true, the search starts from the center point between aStartPoint and aEndPoint in both directions
fSearchGap	float	0	Optional width of a gap (>= 0, centered between aStartPoint and aEndPoint), that is neglected for searching edges (can reduce execution time). The 2 edges to search for must be on different sides of the gap.
nSubpixelsIterations	ULONG	10	Specifies the number of subpixels (for INTERPOLATION, 10 - 20 usually is sufficient) or maximum number of iterations for optimizing the parameters (for APPROX_ERF and APPROX_GAUSSIAN, 50 - 100 usually is sufficient)
fApproxPrecision	float	0.001f	Specifies the approximation precision for APPROX_ERF and APPROX_GAUSSIAN (0.001 usually is sufficient, unused for INTERPOLATION)
eAlgorithm	ETcVnEdgeDetectionAlgorithm	EDA_INTERPOLATION	Selection of the edge detection algorithm
pipEdgePoints1	ITcVnContainer**	nullptr	Returns the detected edge points of the edge near aStartPoint (optional, set to 0 if not required; ContainerType_Vector_TcVnPoint2_REAL)
pipEdgePoints2	ITcVnContainer**	nullptr	Returns the detected edge points of the edge near aEndPoint (optional, set to 0 if not required; ContainerType_Vector_TcVnPoint2_REAL)
pipDistances	ITcVnContainer**	nullptr	Returns the distances between the detected edge points (optional, set to 0 if not required; ContainerType_Vector_REAL)

Return value

HRESULT

Required License

TC3 Vision Metrology 2D

System Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT V3.1. 4024.44 or later	PC or CX (x64) with PL50, e.g. Intel 4-core Atom CPU	Tc3_Vision