Detect circles seen by a webcam with OpenCV

• OpenCV
• GoCV

Both can be installed by following the steps below (taken from this guide)

go get -u -d gocv.io/x/gocv

cd $GOPATH/src/gocv.io/x/gocv
make install

The webcam ID is hardcoded into the code and can be changed by changing the parameter in this line

webcam, _ := gocv.OpenVideoCapture(1)

The Circle Hough Transform which is used to detect the circles can be configured by changing the parameters in the following code block

gocv.HoughCirclesWithParams(
    img,
    &circles,
    gocv.HoughGradient,
    1, // dp
    float64(img.Rows()/8), // minDist
    75, // param1
    40, // param2
    3, // minRadius
    60,  // maxRadius
)

An explanation of the different parameters can be found on the OpenCV documentation pages here