FindReferenceKeyPointsInImageBRISK

Searches a reference image, represented by its BRISK keypoints and corresponding descriptors, in a given source image.
Can use available TwinCAT Job Tasks for executing parallel code regions.

Syntax

Definition:

HRESULT FindReferenceKeyPointsInImageBRISK(
    HRESULT                  hrPrev,
    ITcVnImage*              ipSrcImage,
    ITcVnContainer*          ipRefKeyPoints,
    ITcVnImage*              ipRefDescriptors,
    ULONG                    nRefImageWidth,
    ULONG                    nRefImageHeight,
    ITcVnContainer*&         ipEdgePoints,
    float                    fMaxDist,
    float                    fMaxKnnRatio,
    TcVnMatrix3x3_LREAL&     aPerspectiveTransform,
    ULONG&                   nNumberOfGoodMatches,
    ULONG&                   nNumberOfInliers,
    ETcVnNormalizationType   eNormType = NT_HAMMING,
    ITcVnImage*              ipSrcImageMask = nullptr,
    TcVnParamsBRISK&         stBriskParams = {30, 3, 1},
    ETcVnEstimationAlgorithm eAlgorithm = EA_RANSAC,
    double                   fReprojThreshold = 3,
    ULONG                    nMaxIterations = 2000,
    double                   fConfidence = 0.995
)

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
ipRefKeyPoints	ITcVnContainer*		KeyPoints of the reference image, e.g. computed with F_VN_KeyPointsAndDescriptorsBRISK (ContainerType_Vector_TcVnKeyPoint)
ipRefDescriptors	ITcVnImage*		Descriptors of the reference image KeyPoints, e.g. computed with F_VN_KeyPointsAndDescriptorsBRISK
nRefImageWidth	ULONG		Width of the reference image in pixels
nRefImageHeight	ULONG		Height of the reference image in pixels
ipEdgePoints	ITcVnContainer*&		Returns a container with the 4 edge points of the reference image transformed into ipSrcImage coordinates (ContainerType_Vector_TcVnPoint2_REAL)
fMaxDist	float		Maximum allowed descriptor distance (-1 disables this filter criterion)
fMaxKnnRatio	float		Maximum allowed distance ratio between first and second best match ([0..1], -1 disables this filter criterion)
aPerspectiveTransform	TcVnMatrix3x3_LREAL&		Returns the perspective transformation matrix, which transforms the reference points to the source points
nNumberOfGoodMatches	ULONG&		Return the number of good matches
nNumberOfInliers	ULONG&		Return the number of inlier matches
eNormType	ETcVnNormalizationType	NT_HAMMING	Normalization type used for descriptor matching
ipSrcImageMask	ITcVnImage*	nullptr	Mask to specify, where to look for keypoints in ipSrcImage (set to 0 if no mask required)
stBriskParams	TcVnParamsBRISK&	{30, 3, 1}	Parameters to configure the keypoint and descriptor computation for ipSrcImage (resulting descriptors must be compatible to ipRefDescriptors!)
eAlgorithm	ETcVnEstimationAlgorithm	EA_RANSAC	Estimation algorithm used for computing the perspective transformation between the two point sets
fReprojThreshold	double	3	Maximum allowed reprojection error to treat a point pair as an inlier (only used if eAlgorithm is RANSAC, RHO)
nMaxIterations	ULONG	2000	Maximum number of RANSAC iterations
fConfidence	double	0.995	Confidence (0..1)

Return value

HRESULT

Required License

TC3 Vision Matching

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