F_VN_AngleAndDegreeOfLinearPolarization

Computes the Angle and the Degree of Linear Polarization (AoLP, DoLP) from the four polarization angle images (result of DemosaicPolarizedImage).
Can use available TwinCAT Job Tasks for executing parallel code regions.

Syntax

Definition:

FUNCTION F_VN_AngleAndDegreeOfLinearPolarization : HRESULT
VAR_INPUT
    ip0Deg    : ITcVnImage;
    ip45Deg   : ITcVnImage;
    ip90Deg   : ITcVnImage;
    ip135Deg  : ITcVnImage;
    ipAoLP    : Reference To  ITcVnImage;
    ipDoLP    : Reference To  ITcVnImage;
    eDestType : ETcVnElementType;
    hrPrev    : HRESULT;
END_VAR

Inputs

Name	Type	Description
ip0Deg	ITcVnImage	The 0° component of the polarized image (USINT or UINT, 1 or 3 channels)
ip45Deg	ITcVnImage	The 45° component of the polarized image (USINT or UINT, 1 or 3 channels)
ip90Deg	ITcVnImage	The 90° component of the polarized image (USINT or UINT, 1 or 3 channels)
ip135Deg	ITcVnImage	The 135° component of the polarized image (USINT or UINT, 1 or 3 channels)
ipAoLP	Reference To ITcVnImage	Returns the Angle of Linear Polarization (AoLP) image (Optional, set to 0 if not required. Must be different from the source images! An appropriate destination image will be created if required.)
ipDoLP	Reference To ITcVnImage	Returns the Degree of Linear Polarization (DoLP) image (Optional, set to 0 if not required. Must be different from the source images! An appropriate destination image will be created if required.)
eDestType	ETcVnElementType	Element type of the output images (ET_REAL or ET_USINT). For ET_REAL, AoLP is in the range of [-pi/2, pi/2] and DoLP in [0, 1]. For ET_USINT, both are scaled to a range of [0, 255].
hrPrev	HRESULT	HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)

Return value

HRESULT

Further information

The F_VN_AngleAndDegreeOfLinearPolarization function calculates the angle of linear polarization (AoLP) and the degree of linear polarization (DoLP) from the four polarization angle images. These four images are the result of the F_VN_DemosaicPolarizedImage function.

The AoLP describes the orientation of the polarization plane, while the DoLP indicates the degree to which the light at a pixel is polarized. Both quantities are suitable, for example, for visualizing material properties, surface orientations, or stresses that are not discernible in a conventional intensity image.

Parameter

Input images of the polarization angles

The four input images ip0Deg, ip45Deg, ip90Deg, and ip135Deg represent the separated polarization angles (0°, 45°, 90°, and 135°). Each image must be of the type USINT (8 bits) or UINT (16 bits) and have 1 or 3 channels.

Result Images (AoLP and DoLP)

The angle of linear polarization (AoLP) is returned in image ipAoLP, and the degree of linear polarization (DoLP) is returned in image ipDoLP. Both parameters can be set to 0 if the corresponding output is not needed.

Output element type

The parameter eDestType, of type ETcVnElementType, specifies the element type of the output images:

TCVN_ET_REAL: The AoLP is issued in the range of [−π/2, π/2] and the DoLP in the range of [0, 1].
TCVN_ET_USINT: Both values are scaled to the range [0, 255].

Required License

TC3 Vision Base

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