LocateEllipse

Syntax

Definition:

HRESULT LocateEllipse(
    HRESULT                     hrPrev,
    ITcVnImage*                 ipSrcImage,
    TcVnRotatedRectangle&       stEllipse,
    TcVnPoint2_REAL&            aCenter,
    float                       fSearchRadius,
    ETcVnEdgeDirection          eEdgeDirection,
    float                       fMinStrength,
    ULONG                       nMaxThickness = 10,
    bool                        bInvertSearchDirection = false,
    float                       fMinSearchRadius = 0,
    ULONG                       nSubpixelsIterations = 10,
    ULONG                       nSearchLines = 92,
    float                       fApproxPrecision = 0.001f,
    ETcVnEdgeDetectionAlgorithm eAlgorithm = EDA_INTERPOLATION,
    ITcVnContainer**            pipContourPoints = nullptr,
    float                       fRangeCutoffFactor = 0.135f
)

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)
stEllipse	TcVnRotatedRectangle&		Returns the detected ellipse
aCenter	TcVnPoint2_REAL&		The expected ellipse center
fSearchRadius	float		Radius around aCenter to search for edges
eEdgeDirection	ETcVnEdgeDirection		Specification of the edge direction to search for (from center to outside ellipse or other way round, if bInvertSearchDirection is true)
fMinStrength	float		Specification of the minimum strength (intensity difference) of the edge to search for
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 outside the ellipse in direction of the center
fMinSearchRadius	float	0	Radius around aCenter to skip before starting to search for edges (e.g. to save time or if the center contains edges that should be ignored)
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)
nSearchLines	ULONG	92	Specifies the amount of search lines, which are equally distributed in all directions (must be >= 8 and a multiple of 4)
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
pipContourPoints	ITcVnContainer**	nullptr	Returns the subpixel accurate ellipse contour (optional, set to 0 if not required; ContainerType_Vector_TcVnPoint2_REAL; Non-zero interface pointers are reused.)
fRangeCutoffFactor	float	0.135f	Relative edge strength factor to cut off the range of pixels used for approximation. Negative numbers are valid to include noise, i.e. intensity differences in the other direction. At most nMaxThickness pixels are used in each direction.

Return value

HRESULT

Required License

TC3 Vision Metrology 2D

System Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT V3.1.4024.59 or later	PC or CX (x64) with min. PL50, e.g. Intel 4-core Atom CPU	Tc3_Vision