F_VN_FindReferenceKeyPointsInImageORBExp

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

Syntax

Definition:

FUNCTION F_VN_FindReferenceKeyPointsInImageORBExp : HRESULT
VAR_INPUT
    ipSrcImage            : ITcVnImage;
    ipRefKeyPoints        : ITcVnContainer;
    ipRefDescriptors      : ITcVnImage;
    nRefImageWidth        : UDINT;
    nRefImageHeight       : UDINT;
    ipEdgePoints          : Reference To  ITcVnContainer;
    fMaxDist              : REAL;
    fMaxKnnRatio          : REAL;
    eNormType             : ETcVnNormalizationType;
    ipSrcImageMask        : ITcVnImage;
END_VAR
VAR_IN_OUT
    stOrbParams           : TcVnParamsORB;
END_VAR
VAR_INPUT
    eAlgorithm            : ETcVnEstimationAlgorithm;
    fReprojThreshold      : LREAL;
    nMaxIterations        : UDINT;
    fConfidence           : LREAL;
    hrPrev                : HRESULT;
END_VAR
VAR_OUTPUT
    aPerspectiveTransform : TcVnMatrix3x3_LREAL;
    nNumberOfGoodMatches  : UDINT;
    nNumberOfInliers      : UDINT;
END_VAR

Inputs

Name	Type	Description
ipSrcImage	ITcVnImage	Source image
ipRefKeyPoints	ITcVnContainer	KeyPoints of the reference image, e.g. computed with F_VN_KeyPointsAndDescriptorsORB (ContainerType_Vector_TcVnKeyPoint)
ipRefDescriptors	ITcVnImage	Descriptors of the reference image KeyPoints, e.g. computed with F_VN_KeyPointsAndDescriptorsORB
nRefImageWidth	UDINT	Width of the reference image in pixels
nRefImageHeight	UDINT	Height of the reference image in pixels
ipEdgePoints	Reference To ITcVnContainer	Returns a container with the 4 edge points of the reference image transformed into ipSrcImage coordinates (ContainerType_Vector_TcVnPoint2_REAL)
fMaxDist	REAL	Maximum allowed descriptor distance (-1 disables this filter criterion)
fMaxKnnRatio	REAL	Maximum allowed distance ratio between first and second best match ([0..1], -1 disables this filter criterion)
eNormType	ETcVnNormalizationType	Normalization type used for descriptor matching (HAMMING recommended for ORB, HAMMING2 if the ORB nBriefPoints parameter is 3 or 4)
ipSrcImageMask	ITcVnImage	Mask to specify, where to look for keypoints in ipSrcImage (set to 0 if no mask required)
eAlgorithm	ETcVnEstimationAlgorithm	Estimation algorithm used for computing the perspective transformation between the two point sets
fReprojThreshold	LREAL	Maximum allowed reprojection error to treat a point pair as an inlier (only used if eAlgorithm is RANSAC, RHO)
nMaxIterations	UDINT	Maximum number of RANSAC iterations
fConfidence	LREAL	Confidence (0..1)
hrPrev	HRESULT	HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)

In/Outputs

Name	Type	Description
stOrbParams	TcVnParamsORB	Parameters to configure the keypoint and descriptor computation for ipSrcImage (resulting descriptors must be compatible to ipRefDescriptors!)

Outputs

Name	Type	Description
aPerspectiveTransform	TcVnMatrix3x3_LREAL	Returns the perspective transformation matrix, which transforms the reference points to the source points
nNumberOfGoodMatches	UDINT	Return the number of good matches
nNumberOfInliers	UDINT	Return the number of inlier matches

Return value

HRESULT

Required License

TC3 Vision Matching

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