F_VN_HoughCirclesExp

F_VN_HoughCirclesExp 1:

Search for circles using the Hough transform. (expert function)
Can use available TwinCAT Job Tasks for executing parallel code regions.
Can return partial results when canceled by Watchdog.

Syntax

Definition:

FUNCTION F_VN_HoughCirclesExp : HRESULT
VAR_INPUT
    ipSrcImage    : ITcVnImage;
    ipCircles     : Reference To ITcVnContainer;
    fInvAccuRatio : LREAL;
    fMinDist      : LREAL;
    eHoughMethod  : ETcVnHoughMethod;
    fParam1       : LREAL;
    fParam2       : LREAL;
    nMinRadius    : UDINT;
    nMaxRadius    : UDINT;
    hrPrev        : HRESULT;
END_VAR

F_VN_HoughCirclesExp 2: Inputs

Name

Type

Description

ipSrcImage

ITcVnImage

Source image (USINT, 1 channel, gray-level)

ipCircles

Reference To ITcVnContainer

Returns a container which is filled with the found circles (ContainerType_Vector_TcVnVector3_REAL; Each container element contains the x coordinate of the circle center [0], the y coordinate of the circle center [1], and the radius [2], respectively. Non-zero interface pointers are reused.)

fInvAccuRatio

LREAL

Inverted ratio of the accumulator size in relation to the source image's size (must be > 0. A value of 2 means that the size is halved in both directions.)

fMinDist

LREAL

Smallest allowed distance of two circles (must be > 0)

eHoughMethod

ETcVnHoughMethod

Hough method to use (GRADIENT or GRADIENT_ALT)

fParam1

LREAL

First method specific parameter (GRADIENT, GRADIENT_ALT: upper threshold for canny edge detection, which must be > 0)

fParam2

LREAL

Second method specific parameter (GRADIENT: accumulator threshold for detecting circle centers, which must be > 0. GRADIENT_ALT: required circle perfectness, which must be > 0 and < 1, 1 would be a perfect circle)

nMinRadius

UDINT

Minimum circle radius allowed

nMaxRadius

UDINT

Maximum circle radius allowed (if 0, the value is internally set to max(image rows, image columns))

hrPrev

HRESULT

HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.)

F_VN_HoughCirclesExp 3: 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