F_VN_DecomposeHomographyExp

Decompose a homography matrix and verify four solutions of rotation, translation, and plane normal. It uses visible reference points being in front of the camera to confirm which solution(s) of the four solutions (maximum two solutions) are consistent with all reference points.

Syntax

Definition:

FUNCTION F_VN_DecomposeHomographyExp : HRESULT
VAR_IN_OUT
    aHomography         : TcVnMatrix3x3_LREAL;
    aCameraMatrix       : TcVnMatrix3x3_LREAL;
    aRotationMatrixA    : TcVnMatrix3x3_LREAL;
    aTranslationVectorA : TcVnVector3_LREAL;
    aNormVectorA        : TcVnVector3_LREAL;
    aRotationMatrixB    : TcVnMatrix3x3_LREAL;
    aTranslationVectorB : TcVnVector3_LREAL;
    aNormVectorB        : TcVnVector3_LREAL;
END_VAR
VAR_INPUT
    ipPointsSrc         : ITcVnContainer;
    ipPointsDes         : ITcVnContainer;
    ipInlierMask        : ITcVnContainer;
    hrPrev              : HRESULT;
END_VAR
VAR_OUTPUT
    nSolutions          : UDINT;
END_VAR

Inputs

Name	Type	Description
ipPointsSrc	ITcVnContainer	Container with source points (ContainerType_Vector_TcVnPoint2_REAL)
ipPointsDes	ITcVnContainer	Container with destination points (same number as ipPoints1, ContainerType_Vector_TcVnPoint2_REAL)
ipInlierMask	ITcVnContainer	A mask marking the inliers (optional, set to 0 if not available; ContainerType_Vector_SINT or ContainerType_Vector_USINT)
hrPrev	HRESULT	HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)

In/Outputs

Name	Type	Description
aHomography	TcVnMatrix3x3_LREAL	Homography matrix (a perspective transformation between two planes)
aCameraMatrix	TcVnMatrix3x3_LREAL	Camera matrix
aRotationMatrixA	TcVnMatrix3x3_LREAL	Rotation matrix of the first solution (Ra)
aTranslationVectorA	TcVnVector3_LREAL	Translation vector of the first solution (Ta)
aNormVectorA	TcVnVector3_LREAL	Norm vector of the first solution (Na)
aRotationMatrixB	TcVnMatrix3x3_LREAL	Rotation matrix of the second solution (Rb)
aTranslationVectorB	TcVnVector3_LREAL	Translation vector of the second solution (Tb)
aNormVectorB	TcVnVector3_LREAL	Norm vector of the second solution (Nb)

Outputs

Name	Type	Description
nSolutions	UDINT	Return the number of true potential solutions [0,1, or 2]. 0: no true potential solutions for the given corresponding points are confirmed. 1: the solution (Ra, Ta, Na) is confirmed. 2: both solution (Ra, Ta, Na) and (Rb, Tb, Nb) are confirmed. In all cases the function returns two solutions (Ra, Ta, Nb) and (Rb, Tb, Nb). The third and the fourth solutions can be calculated as follows: (Ra, -Ta, -Na) and (Rb, -Tb, -Nb).

Return value

HRESULT

Required License

TC3 Vision Base

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