在OpenCV中绘制成角度的矩形 [英] Drawing angled rectangles in OpenCV

问题描述

我正在使用OpenCV和python处理涉及人体跟踪的项目，并且正在使用HSV值查找肤色，然后在其周围绘制一个框.

I am using OpenCV and python to work on a project that involves body tracking, and I am using HSV values to find a skin tone then draw a box around it.

尽管我可以找到被跟踪的对象并在其周围画一个框，但矩形始终是垂直的，并且我想知道矩形是否存在角度，以便它们更好地显示检测到的对象，有点类似于minEnclosingCircle函数，但是使用矩形

However although I can find the tracked object and draw a box around it the rectangles are always vertical, and I would like to know if there is anyway angle the rectangles so they better show the detected object, somewhat like the minEnclosingCircle function, but using a rectangle

图像可能解释了我正在寻找的更好的东西.我得到的盒子是绿色的，而我要寻找的是黄色的.如您所见，蒙版显示和带角度的矩形也将更好地包围所选区域.我还包括原始图像.

The images probably explain what I am looking for better. The boxes that I am getting are green, and what I'm looking for I have drawn on in yellow. As you can see the mask shows and angled rectangle would also better encompass the selected area. I have also included the original image.

我的代码是:

    import numpy as np
    import cv2

    # Input image
    image = cv2.imread('TestIn.png')

    # Converts to grey for better reulsts
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

    # Converts to HSV
    hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)

    # HSV values
    lower_skin = np.array([5,36,53])
    upper_skin = np.array([19,120,125])

    mask = cv2.inRange(hsv, lower_skin, upper_skin)

    mask = cv2.erode(mask, None, iterations=2)
    mask = cv2.dilate(mask, None, iterations=2)

    # Finds contours
    im2, cnts, hierarchy = cv2.findContours(mask.copy(), cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    # Draws contours
    for c in cnts:
        if cv2.contourArea(c) < 3000:
            continue

        (x, y, w, h) = cv2.boundingRect(c)
        cv2.rectangle(image, (x,y), (x+w,y+h), (0, 255, 0), 2)
cv2.imshow('mask', mask)
cv2.imshow('image', image)
cv2.waitKey(0)
cv2.destroyAllWindows()

输入图片:

输出图像(绿色的输出框，黄色的所需框):

Output image (output boxes in green, desired boxes in yellow):

推荐答案

您需要使用 cv2.boxPoints(...) 以获得表示多边形的点序列，其格式可以由其他OpenCV绘图功能使用，例如

You need to use cv2.minAreaRect(...) and then cv2.boxPoints(...) to obtain a sequence of points representing the polygon in a format that can be used by other OpenCV drawing functions, such as cv2.drawContours(...) or cv2.polylines(...).

基于示例在OpenCV文档中，我向您的代码中添加了一些语句以实现所需的结果:

Based on the example in OpenCV documentation I added few statements to your code to achieve the desired result:

import numpy as np
import cv2

# Input image
image = cv2.imread('oaHUs.jpg')

# Converts to grey for better reulsts
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Converts to HSV
hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)

# HSV values
lower_skin = np.array([5,36,53])
upper_skin = np.array([19,120,125])

mask = cv2.inRange(hsv, lower_skin, upper_skin)

mask = cv2.erode(mask, None, iterations=2)
mask = cv2.dilate(mask, None, iterations=2)

# Finds contours
im2, cnts, hierarchy = cv2.findContours(mask.copy(), cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

# Draws contours
for c in cnts:
    if cv2.contourArea(c) < 3000:
        continue

    (x, y, w, h) = cv2.boundingRect(c)
    cv2.rectangle(image, (x,y), (x+w,y+h), (0, 255, 0), 2)

    ## BEGIN - draw rotated rectangle
    rect = cv2.minAreaRect(c)
    box = cv2.boxPoints(rect)
    box = np.int0(box)
    cv2.drawContours(image,[box],0,(0,191,255),2)
    ## END - draw rotated rectangle

cv2.imwrite('out.png', image)

输出:

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