Detect the center coordinates of shapes in Python.

This repo is for detecting center coordinates of various type of shapes.

Install

If you have manually installed module previously , you don't need to installation process.
Otherwise, open the cmd and run the command to install it.

cv2 :

pip install opencv-python

Matplotlib :

pip install matplotlib

Numpy :

pip install numpy

Example

Here is an example on this project :

This example will detect the center coordinates various shapes
(Triangle, Circle, Oval, Square ... etc .)

print("coordinates of centers:")
for i in contours:
    M = cv.moments(i)
    if M['m00'] != 0:
        cx = int(M['m10']/M['m00'])
        cy = int(M['m01']/M['m00'])
        cv.drawContours(image, [i], -1, (0, 255, 0), 1)
        cv.circle(image, (cx, cy), 7, (0, 0, 255), -1)
        cv.putText(image, "center", (cx - 70, cy - 20), cv.FONT_HERSHEY_SIMPLEX, 1.5, (0, 0, 0), 2)
        print(f"x: {cx} y: {cy}")
print("number of shapes detected: ", len(contours))

cv.imwrite("image.png", image)

Using cv2.moments() to calculate the moments from contour, and seek the center coordinates using the following formula.

Detect the center coordinates :

Limitatioins

It has some limitations of Boundary recongnition due to the setting boundary value of the shapes.

It may occur a problem of poor-recognition in the case of light colors.

ret, thresh = cv.threshold(blur, 225, 255,cv.THRESH_BINARY_INV)

Currently, the threshold value is set to 225. It is necessary to closely adjust the value.