本文介绍如何使用python语言实现角度测量,程序包括鼠标选点、直线斜率计算、角度计算三个子程序和一个主程序。最终实现效果:在图片上用鼠标确认三点,程序将会显示由此三点确定的角度,如下图所示。
1、鼠标选点
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# -*- 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() |
while循环内cv2.setMouseCallback('Image',mousePoints)为鼠标中断触发事件的开启函数,作用是当在Image图片上鼠标触发中断事件时,程序跳转到mousePoints()中断服务函数内,并给mousePoints()的五个入口参数event,x,y,flags,params赋值。其中, event是cv2_EVENT_* (MouseEventTypes)类型的变量,为鼠标触发中断事件的类型;x和y为鼠标触发中断事件时在image图像的横纵坐标;flags是cv2_EVENT_FLAG_* (MouseEventFlags)类型的变量,为特殊中断事件的标志位;param是用户自定义的参数。本文的程序中使用 EVENT_LBUTTONDOW#左键点击触发事件,当鼠标左键点击时,标注该点并记录其坐标。
event的赋值:
- EVENT_MOUSEMOVE #滑动
- EVENT_LBUTTONDOWN #左键点击
- EVENT_RBUTTONDOWN #右键点击
- EVENT_MBUTTONDOWN #中键点击
- EVENT_LBUTTONUP #左键放开
- EVENT_RBUTTONUP #右键放开
- EVENT_MBUTTONUP #中键放开
- EVENT_LBUTTONDBLCLK #左键双击
- EVENT_RBUTTONDBLCLK #右键双击
- EVENT_MBUTTONDBLCLK #中键双击
2、角度计算
由1可以得到鼠标点击位置处的坐标,我们将其放入pointList列表内。当列表内的坐标数目为3的倍数时调用getAngle()函数,计算出三点确定的两条直线的夹角。
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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 )) |
由直线的两点式方程可得直线的倾斜角为angle = arctan(y2-y1,x2-x1),则两条直线的夹角为angle0 =angle1-angle2 = arctan(y2-y1,x2-x1) - arctan(y2-y3,x2-x3)。以上函数便可根据三点的坐标值求其形成夹角的角度。
3、完整程序
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# -*- 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() |
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原文链接:https://blog.csdn.net/qq_42242399/article/details/123259393