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  • python+opencv中最近出现的一些变化( OpenCV 官方的 Python tutorial目前好像还没有改过来?) 记一次全景图像的拼接

    最近在学习过程中发现opencv有了很多变动, OpenCV 官方的 Python tutorial目前好像还没有改过来,导致大家在学习上面都出现了一些问题,现在做一个小小的罗列,希望对大家有用

    做的是关于全景图像的拼接,关于sift和surf的语法之后有需要会另开文章具体阐述,此篇主要是解决大家困惑许久的问题。

    笔者python3.x

    首先是安装上,必须先后安装pip install opencv_python和pip install opencv-contrib-python==3.3.0.10后面一个一定要指定版本号,因为版本上面最新的opencv-contrib-python-3.4.5.20版本好像申请了什么专利,所以我们可能无法调用的,安装上要是出现了报错,先别急着写在,重新运行一次语句,基本上就可能可以了。

    然后是关于sift和surf这两条语句上面,它的语法函数也出现了变化,具体可以参考这个

    http://answers.opencv.org/question/52130/300-python-cv2-module-cannot-find-siftsurforb/

    好像是最近才修改的,真的走了很多弯路才走通。

    #这里的代码有改动之后才能用

    #sift = cv.xfeatures2d_SIFT().create()修改为

    sift = cv2.xfeatures2d.SIFT_create()

     

    hessian=400
    #surf=cv2.SURF(hessian)修改为

    surf=cv2.xfeatures2d.SURF_create(hessian)

     

    下面给出两个代码,是借鉴了网友的,但是对于报错的部分和需要改正的点都已经纠错完毕了,希望对大家有所帮助。有其他的bug也欢迎留言。

    示例1

     

    6.jpg

    7.jpg

     效果图

    #coding: utf-8
    import numpy as np
    import cv2
     
    leftgray = cv2.imread('6.jpg')
    rightgray = cv2.imread('7.jpg')
     
    hessian=400
    surf=cv2.xfeatures2d.SURF_create(hessian)
    #surf=cv2.SURF(hessian) #将Hessian Threshold设置为400,阈值越大能检测的特征就越少
    kp1,des1=surf.detectAndCompute(leftgray,None)  #查找关键点和描述符
    kp2,des2=surf.detectAndCompute(rightgray,None)
     
     
    FLANN_INDEX_KDTREE=0   #建立FLANN匹配器的参数
    indexParams=dict(algorithm=FLANN_INDEX_KDTREE,trees=5) #配置索引,密度树的数量为5
    searchParams=dict(checks=50)    #指定递归次数
    #FlannBasedMatcher:是目前最快的特征匹配算法(最近邻搜索)
    flann=cv2.FlannBasedMatcher(indexParams,searchParams)  #建立匹配器
    matches=flann.knnMatch(des1,des2,k=2)  #得出匹配的关键点
     
    good=[]
    #提取优秀的特征点
    for m,n in matches:
        if m.distance < 0.7*n.distance: #如果第一个邻近距离比第二个邻近距离的0.7倍小,则保留
            good.append(m)
    src_pts = np.array([ kp1[m.queryIdx].pt for m in good])    #查询图像的特征描述子索引
    dst_pts = np.array([ kp2[m.trainIdx].pt for m in good])    #训练(模板)图像的特征描述子索引
    H=cv2.findHomography(src_pts,dst_pts)         #生成变换矩阵
    h,w=leftgray.shape[:2]
    h1,w1=rightgray.shape[:2]
    shft=np.array([[1.0,0,w],[0,1.0,0],[0,0,1.0]])
    M=np.dot(shft,H[0])            #获取左边图像到右边图像的投影映射关系
    dst_corners=cv2.warpPerspective(leftgray,M,(w*2,h))#透视变换,新图像可容纳完整的两幅图
    cv2.imshow('tiledImg1',dst_corners)   #显示,第一幅图已在标准位置
    dst_corners[0:h,w:w*2]=rightgray  #将第二幅图放在右侧
    #cv2.imwrite('tiled.jpg',dst_corners)
    cv2.imshow('tiledImg',dst_corners)
    cv2.imshow('leftgray',leftgray)
    cv2.imshow('rightgray',rightgray)
    cv2.waitKey()
    cv2.destroyAllWindows()

    示例2

    test1.jpg

    test2.jpg

     效果图

    import numpy as np
    import cv2 as cv
    from matplotlib import pyplot as plt
    
    if __name__ == '__main__':
        top, bot, left, right = 100, 100, 0, 500
        img1 = cv.imread('test1.jpg')
        img2 = cv.imread('test2.jpg')
        srcImg = cv.copyMakeBorder(img1, top, bot, left, right, cv.BORDER_CONSTANT, value=(0, 0, 0))
        testImg = cv.copyMakeBorder(img2, top, bot, left, right, cv.BORDER_CONSTANT, value=(0, 0, 0))
        img1gray = cv.cvtColor(srcImg, cv.COLOR_BGR2GRAY)
        img2gray = cv.cvtColor(testImg, cv.COLOR_BGR2GRAY)
        
        #这里的代码有改动之后才能用
        #sift = cv.xfeatures2d_SIFT().create()
        sift = cv2.xfeatures2d.SIFT_create()
        
        # find the keypoints and descriptors with SIFT
        kp1, des1 = sift.detectAndCompute(img1gray, None)
        kp2, des2 = sift.detectAndCompute(img2gray, None)
        # FLANN parameters
        FLANN_INDEX_KDTREE = 1
        index_params = dict(algorithm=FLANN_INDEX_KDTREE, trees=5)
        search_params = dict(checks=50)
        flann = cv.FlannBasedMatcher(index_params, search_params)
        matches = flann.knnMatch(des1, des2, k=2)
    
        # Need to draw only good matches, so create a mask
        matchesMask = [[0, 0] for i in range(len(matches))]
    
        good = []
        pts1 = []
        pts2 = []
        # ratio test as per Lowe's paper
        for i, (m, n) in enumerate(matches):
            if m.distance < 0.7*n.distance:
                good.append(m)
                pts2.append(kp2[m.trainIdx].pt)
                pts1.append(kp1[m.queryIdx].pt)
                matchesMask[i] = [1, 0]
    
        draw_params = dict(matchColor=(0, 255, 0),
                           singlePointColor=(255, 0, 0),
                           matchesMask=matchesMask,
                           flags=0)
        img3 = cv.drawMatchesKnn(img1gray, kp1, img2gray, kp2, matches, None, **draw_params)
        plt.imshow(img3, ), plt.show()
    
        rows, cols = srcImg.shape[:2]
        MIN_MATCH_COUNT = 10
        if len(good) > MIN_MATCH_COUNT:
            src_pts = np.float32([kp1[m.queryIdx].pt for m in good]).reshape(-1, 1, 2)
            dst_pts = np.float32([kp2[m.trainIdx].pt for m in good]).reshape(-1, 1, 2)
            M, mask = cv.findHomography(src_pts, dst_pts, cv.RANSAC, 5.0)
            warpImg = cv.warpPerspective(testImg, np.array(M), (testImg.shape[1], testImg.shape[0]), flags=cv.WARP_INVERSE_MAP)
    
            for col in range(0, cols):
                if srcImg[:, col].any() and warpImg[:, col].any():
                    left = col
                    break
            for col in range(cols-1, 0, -1):
                if srcImg[:, col].any() and warpImg[:, col].any():
                    right = col
                    break
    
            res = np.zeros([rows, cols, 3], np.uint8)
            for row in range(0, rows):
                for col in range(0, cols):
                    if not srcImg[row, col].any():
                        res[row, col] = warpImg[row, col]
                    elif not warpImg[row, col].any():
                        res[row, col] = srcImg[row, col]
                    else:
                        srcImgLen = float(abs(col - left))
                        testImgLen = float(abs(col - right))
                        alpha = srcImgLen / (srcImgLen + testImgLen)
                        res[row, col] = np.clip(srcImg[row, col] * (1-alpha) + warpImg[row, col] * alpha, 0, 255)
    
            # opencv is bgr, matplotlib is rgb
            res = cv.cvtColor(res, cv.COLOR_BGR2RGB)
            # show the result
            plt.figure()
            plt.imshow(res)
            plt.show()
        else:
            print("Not enough matches are found - {}/{}".format(len(good), MIN_MATCH_COUNT))
            matchesMask = None
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  • 原文地址:https://www.cnblogs.com/xingnie/p/10230278.html
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