F_VN_DetectPatternPointsExp

Detects calibration pattern points (circles) within the provided image. (expert function)
Can use available TwinCAT Job Tasks for executing parallel code regions.

Syntax

Definition:

FUNCTION F_VN_DetectPatternPointsExp : HRESULT
VAR_INPUT
    ipSrcImage            : ITcVnImage;
    ipPatternPoints       : Reference To  ITcVnContainer;
END_VAR
VAR_IN_OUT
    stBlobDetectionParams : TcVnParamsBlobDetection;
END_VAR
VAR_INPUT
    nNumberOfPoints       : UDINT;
    fSizeDiffThresFactor  : REAL;
    bSubpixelAccuracy     : BOOL;
    eEdgeDirection        : ETcVnEdgeDirection;
    fMinStrength          : REAL;
    nMaxThickness         : UDINT;
    nSubpixelsIterations  : UDINT;
    nSearchLines          : UDINT;
    fApproxPrecision      : REAL;
    eAlgorithm            : ETcVnEdgeDetectionAlgorithm;
    hrPrev                : HRESULT;
END_VAR

Inputs

Name	Type	Description
ipSrcImage	ITcVnImage	Source image (USINT, 1 channel)
ipPatternPoints	Reference To ITcVnContainer	Returns the pattern point positions (ContainerType_Vector_TcVnPoint2_REAL; Non-zero interface pointers are reused.)
nNumberOfPoints	UDINT	Expected number of pattern points
fSizeDiffThresFactor	REAL	Threshold for filtering contours by average size
bSubpixelAccuracy	BOOL	If true, the pattern points are detected with subpixel accuracy
eEdgeDirection	ETcVnEdgeDirection	Specification of the edge direction to search for (from center to outside circle)
fMinStrength	REAL	Specification of the minimum strength (intensity difference) of the edge to search for
nMaxThickness	UDINT	Specification of the maximum thickness of the edge to search for, which means fMinStrength must be reached within nMaxThickness pixels
nSubpixelsIterations	UDINT	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	UDINT	Specifies the amount of search lines, which are equally distributed in all directions (must be >= 8 and a multiple of 4)
fApproxPrecision	REAL	Specifies the approximation precision for APPROX_ERF and APPROX_GAUSSIAN (0.001 usually is sufficient, unused for INTERPOLATION)
eAlgorithm	ETcVnEdgeDetectionAlgorithm	Selection of the edge detection algorithm
hrPrev	HRESULT	HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)

In/Outputs

Name	Type	Description
stBlobDetectionParams	TcVnParamsBlobDetection	Parameters to detect and filter contours.

Return value

HRESULT

Required License

TC3 Vision Metrology 2D

System Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT V3.1.4024.54 or later	PC or CX (x64) with PL50, e.g. Intel 4-core Atom CPU	Tc3_Vision