使用坐标绘制和裁剪旋转矩形

Question

I am trying to draw and crop rotated rectangle into opencv python but I don't know how to do it. I have x,y coordinates width and height of rectangle and searched about how to find contours of that x,y coordinates for using cv2.minAreaRect() but can't make it.

I am giving line coordinates and also drawn a line on it to show you.where I want to draw rectangle of height 2 and width same as line. Line Coordinates: x1, y1, x2, y2 = 542, 771, 1757, 977

I can not explain it properly please understand what I want.

I tried it with following script but I don't know how to find contours from x, coordinates

import cv2
import numpy as np


def main():
    img = cv2.imread("/home/infinity/Pictures/1.png")
    # points for test.jpg
    cnt = np.array([
            [[64, 49]],
            [[122, 11]],
            [[391, 326]],
            [[308, 373]]
        ])
    print("shape of cnt: {}".format(cnt.shape))
    rect = cv2.minAreaRect(cnt)
    print("rect: {}".format(rect))

    # the order of the box points: bottom left, top left, top right,
    # bottom right
    box = cv2.boxPoints(rect)
    box = np.int0(box)

    print("bounding box: {}".format(box))
    cv2.drawContours(img, [box], 0, (0, 0, 255), 2)

    # get width and height of the detected rectangle
    width = int(rect[1][0])
    height = int(rect[1][1])

    src_pts = box.astype("float32")
    # corrdinate of the points in box points after the rectangle has been
    # straightened
    dst_pts = np.array([[0, height-1],
                        [0, 0],
                        [width-1, 0],
                        [width-1, height-1]], dtype="float32")

    # the perspective transformation matrix
    M = cv2.getPerspectiveTransform(src_pts, dst_pts)

    # directly warp the rotated rectangle to get the straightened rectangle
    warped = cv2.warpPerspective(img, M, (width, height))

    # cv2.imwrite("crop_img.jpg", warped)
    cv2.waitKey(0)


if __name__ == "__main__":
    main()

Answer 1

It appears to be basically duplicate question to Draw rectangle in OpenCV . It obviously contains a definition of rectangle for OpenCV.

If you're having acutally trouble to get coordinates , then we need to know what is the goal. If the camera has static view, then it would be obviusly trivial, just using an editor like Gimp to read them. I sense it might be a moving camera or some other complication stand in a way...

If you meant something different, you should really express what do you want to achieve .