多条水平线和垂直线未显示

Question

在这里，我尝试使用opencv，霍夫变换来查找水的高度。 该程序包括Canny边缘检测，背景减法，霍夫变换和高度估计。 然后使用高度绘制图表，但这只会检测垂直线。 没有显示多条水平和垂直线。 代码有问题吗？

程序输出：

from imutils.perspective import four_point_transform
from imutils import paths
import numpy as np
import imutils 
import argparse
import cv2
import random
import math
import matplotlib.pyplot as plt

scaling_factorx = 0.8
scaling_factory = 0.8

cap = cv2.VideoCapture(0)
fgbg = cv2.createBackgroundSubtractorMOG2()
cap.set(3,640)
cap.set(4,480)
count = 0
height = []

while(1):

    ret, frame = cap.read()

    if frame is None:
        break
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    edges = cv2.Canny(gray, 1, 100)
    lines = cv2.HoughLinesP(edges, rho = 1,theta = 2*np.pi/180,threshold = 10,minLineLength = 100,maxLineGap = 10);
    if lines is not None:
        for line in lines[0]:
            dot1 = (line[0],line[1])
            dot2 = (line[2],line[3])
            cv2.line(frame, dot1, dot2, (255,0,0), 3)
            length = line[1] - line[3]
            print(length)
            height.append(length)

    cv2.imshow("output", frame)

    frame = cv2.resize(frame, None, fx = scaling_factorx, fy = scaling_factory, interpolation = cv2.INTER_AREA)

    fgmask = fgbg.apply(frame)
    cv2.imshow('frame', fgmask)

    gray_vid = cv2.cvtColor(frame, cv2.IMREAD_GRAYSCALE)
    cv2.imshow('Original', frame)

    edged_frame = cv2.Canny(frame, 1, 100)
    cv2.imshow('Edges', edged_frame)

    if cv2.waitKey(1) & 0xFF ==ord('q'):
        break

x = []
y = []

for i in range(len(height)):
    x.append(i)
    y.append(height[i])

cap.release()
cv2.destroyAllWindows()
print(x,y) 
plt.plot(x, y)  
plt.xlabel('x - axis') 
plt.ylabel('y - axis')  
plt.title('Height') 
plt.show()

Answer 1

您只画一条线，因为for循环线仅循环一条线。

if lines is not None:
    for line in lines: #for each line...not just one of them
        for x1,y1,x2,y2 in line:
            dot1 = (x1,y1)
            dot2 = (x2,y2)
            cv2.line(frame, dot1, dot2, (255,0,0), 3)
            length = y1 - y2
            print(length)
            height.append(length)