cvHoughCircles

[GRUhub]

Hello,

I'm trying to use the cvHoughCircles function but it doesn't work and I'm confused. How get Circle Center and Radius? Thx

procedure TForm1.FindCircles;
const
  Param1 = 100;
  Param2 = 30;
  RadiusMin   = 1;
  RadiusMaks = 300;
var
  GrayImg: TMat;
  Circles: pCvSeq; 
  Circle: pCvSeqBlock; 
  Radius: integer;
  Centre: TPoint;
  Storage: pCvMemStorage;
  i: integer;
  CirclesCount: integer;
begin
  cv.OpenCV.cvtColor(FFrame, GrayImg, COLOR_BGR2GRAY);
  cv.OpenCV.medianBlur(GrayImg, GrayImg, 5);

  try
    Storage := cvCreateMemStorage(0);
    Circles   := cv.OpenCV.cvHoughCircles(@ImgGray, @Storage, CV_HOUGH_GRADIENT, 1, // Error
                      ImgGray.Rows div 16, Param1, Param2, RadiusMin, RadiusMaks);

    if (Circles <> nil)
    then begin
      CirclesCount := Circles^.Total;

      if (CirclesCount > 0)
      then begin
        for i := 0 to CirclesCount - 1 do begin
          Circle := pCvSeqBlock(cvGetSeqElem(Circles, i)); 
          ...
        end;
      end;
    end;
  finally
    cvReleaseMemStorage(@Storage);
    ImgGray.copyTo(FFrame);
  end;
end;

[Laex]

Give a complete example

[GRUhub]

Example.zip

[Laex]

Partial answer for now (since the "Find circles (error)" item doesn't work yet):
For the line() function, the FILLED parameter is not used, since it means - fill the area. For a single line, this doesn't matter - see
https://docs.opencv.org/4.10.0/d6/d6e/group__imgproc__draw.html#ga7078a9fae8c7e7d13d24dac2520ae4a2
Available values ​​- LINE_4, LINE_8, LINE_AA

[Laex]

cvHoughCircles() uses cvArr. It is not TMat.
For TMat you need to use HoughCircles()

[GRUhub]

Thanks for your help. This is my first experience using opencv, but I would also like to ask if the function HoughCircles() must be in this component (I can't find it)? Thank you.

[Laex]

I'll do HoughCircles() this weekend

[Laex]

Done