我正在使用python中的opencv使用shape检测算法。我正在使用库中的轮廓,并且成功检测出一些形状:圆形,矩形和三角形。唯一的问题是,我只需要检测圆形的矩形和八边形。此外,圈子还在运作,但不一致。所以,这是我的代码:
import cv2
import numpy as np
def nothing(x):
# any operation
pass
cap = cv2.VideoCapture(1)
cv2.namedWindow("Trackbars")
cv2.createTrackbar("L-H", "Trackbars", 0, 180, nothing)
cv2.createTrackbar("L-S", "Trackbars", 66, 255, nothing)
cv2.createTrackbar("L-V", "Trackbars", 134, 255, nothing)
cv2.createTrackbar("U-H", "Trackbars", 180, 180, nothing)
cv2.createTrackbar("U-S", "Trackbars", 255, 255, nothing)
cv2.createTrackbar("U-V", "Trackbars", 243, 255, nothing)
font = cv2.FONT_HERSHEY_COMPLEX
while True:
_, frame = cap.read()
hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
l_h = cv2.getTrackbarPos("L-H", "Trackbars")
l_s = cv2.getTrackbarPos("L-S", "Trackbars")
l_v = cv2.getTrackbarPos("L-V", "Trackbars")
u_h = cv2.getTrackbarPos("U-H", "Trackbars")
u_s = cv2.getTrackbarPos("U-S", "Trackbars")
u_v = cv2.getTrackbarPos("U-V", "Trackbars")
lower_yellow = np.array([l_h,l_s, l_v])
upper_yellow = np.array([u_h, u_s, u_v])
mask = cv2.inRange(hsv, lower_yellow, upper_yellow)
kernel = np.ones((5, 5), np.uint8)
mask = cv2.erode(mask, kernel)
# Contours detection
if int(cv2.__version__[0]) > 3:
# Opencv 4.x.x
contours, _ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
else:
# Opencv 3.x.x
_, contours, _ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
for cnt in contours:
area = cv2.contourArea(cnt)
approx = cv2.approxPolyDP(cnt, 0.02*cv2.arcLength(cnt, True), True)
x = approx.ravel()[0]
y = approx.ravel()[1]
if area > 400:
cv2.drawContours(frame, [approx], 0, (0, 0, 0), 5)
if len(approx) == 3:
cv2.putText(frame, "Triangle", (x, y), font, 1, (0, 0, 0))
elif len(approx) == 4:
cv2.putText(frame, "Rectangle", (x, y), font, 1, (0, 0, 0))
elif 10 < len(approx) < 20:
cv2.putText(frame, "Circle", (x, y), font, 1, (0, 0, 0))
cv2.imshow("Frame", frame)
cv2.imshow("Mask", mask)
key = cv2.waitKey(1)
if key == 27:
break
cap.release()
cv2.destroyAllWindows()
我想拥有的是更精确地检测八边形和圆形。
要执行形状检测,我们可以使用轮廓逼近。假设对象是simple形状,这是一种使用阈值+轮廓近似的方法。轮廓近似是基于这样的假设,即曲线可以由一系列短线段近似,这些短线段可用于确定轮廓的形状。例如,三角形具有三个顶点,正方形/矩形具有四个顶点,五边形具有五个顶点,依此类推。]
获得二进制图像。
加载图像,转换为灰度,然后Otsu's threshold获取二进制图像。检测形状。
arcLength
计算轮廓的周长,并使用arcLength
获得实际的轮廓近似值。 输入图像
标签形状
代码
approxPolyDP