Python+OpenCV实现角度测量的示例代码

# -*- coding: utf-8 -*-
 
import cv2
 
path = "picture_mqa\\angle_measure.bmp"
img = cv2.imread(path)
pointsList = []
 
def mousePoints(event,x,y,flags,params):
    if event  == cv2.EVENT_LBUTTONDOWN:
        cv2.circle(img,(x,y),5,(0,0,255),cv2.FILLED)
        print(x,y)
 
while True:
    cv2.imshow('Image', img)
    cv2.setMouseCallback('Image',mousePoints)
    
    key_scan = cv2.waitKey(1) & 0xff 
    
    if key_scan == ord("q"):
        pointsList = []
        img = cv2.imread(path)
    elif key_scan == ord("s"):
        break
    
cv2.destroyAllWindows()  

def gradient(pt1,pt2):
    return ((pt2[1]-pt1[1])/(pt2[0]-pt1[0]))
 
def getAngle(pointsList):
    pt1,pt2,pt3 = pointsList[-3:] 
    m1 = gradient(pt1, pt2)
    m2 = gradient(pt1, pt3)
    angR = abs(math.atan((m2-m1)/(1+m2*m1)))
    angD = round(math.degrees(angR))
    
    cv2.putText(img,str(angD),(pt1[0]-40,pt1[1]-20),cv2.FONT_HERSHEY_COMPLEX,
                1.5,(0,0,255)) 

# -*- coding: utf-8 -*-
'''
测量鼠标点击过的三点形成的角度
'''
import cv2
import math
 
path = "picture_mqa\\angle_measure.bmp"  #图片路径
img = cv2.imread(path)
pointsList = []
 
#鼠标中断触发函数，将鼠标触发事件位置处描点并将该点的坐标值纪录入pointList列表内
#连接相邻三点使其形成一个夹角
def mousePoints(event,x,y,flags,params):
    if event  ==cv2.EVENT_LBUTTONDOWN:
        size = len(pointsList)
        if size != 0 and size%3 !=0:
            cv2.line(img,tuple(pointsList[round((size-1)/3)*3]),(x,y),(0,0,255))
        cv2.circle(img,(x,y),5,(0,0,255),cv2.FILLED)
        pointsList.append([x,y])
 
#由两点的坐标值计算两点所在直线的斜率        
def gradient(pt1,pt2):
    return ((pt2[1]-pt1[1])/(pt2[0]-pt1[0]))
 
#根据相邻的三点计算出其形成夹角的角度值
def getAngle(pointsList):
    pt1,pt2,pt3 = pointsList[-3:] 
    m1 = gradient(pt1, pt2)
    m2 = gradient(pt1, pt3)
    angR = abs(math.atan((m2-m1)/(1+m2*m1)))
    angD = round(math.degrees(angR))
    
    cv2.putText(img,str(angD),(pt1[0]-40,pt1[1]-20),cv2.FONT_HERSHEY_COMPLEX,
                1.5,(0,0,255))       
 
 
while True:
    cv2.imshow('Image', img) #图片显示
    cv2.setMouseCallback('Image',mousePoints) #鼠标触发事件开启
    
    if len(pointsList) % 3 ==0 and len(pointsList)!=0: #鼠标每触发中断3次计算一次其形式夹角的角度值
        getAngle(pointsList)
    
    key_scan = cv2.waitKey(1) & 0xff #键盘扫描
    if key_scan == ord("q"):  #输入'q'时图片刷新
        pointsList = []
        img = cv2.imread(path)
        
    elif key_scan == ord("s"): #输入's'时退出程序
        break
    
cv2.destroyAllWindows()