我在写CV中图片拼接过程中，有段代码如下：

//特征点描述，为特征点匹配做准备
    OrbDescriptorExtractor orbDescriptor;
    vector<Mat> imagesDesc;
    for (int i = 0; i < cvt_s_imgs.size(); i++)
    {
        Mat imageDesc;
        orbDescriptor.compute(cvt_s_imgs[i], keyPoints[i], imageDesc);
        imagesDesc.push_back(imageDesc);
    }
    flann::Index flannIndex(imagesDesc[0], flann::LshIndexParams(12, 20, 2), cvflann::FLANN_DIST_HAMMING);
    vector<DMatch> GoodMatchPoints;
    Mat matchIndex(imagesDesc[1].rows, 2, CV_32SC1), matchDistance(imagesDesc[1].rows, 2, CV_32FC1);
    flannIndex.knnSearch(imagesDesc[1], matchIndex, matchDistance, 2, flann::SearchParams());


    //采用Lowe's 算法选取优秀匹配点
    for (int i = 0; i < matchDistance.rows; i++)
    {
        if (matchDistance.at<float>(i, 0) < 0.6*matchDistance.at<float>(i, 1))
        {
            DMatch dmatches(i, matchIndex.at<int>(i, 0), matchDistance.at<float>(i, 0));
            GoodMatchPoints.push_back(dmatches);
        }
    }
    //将goodmatch点集进行转换
    vector<vector<Point2f>> Points2f;
    vector<Point2f> imagePoint1, imagePoint2;
    Points2f.push_back(imagePoint1);
    Points2f.push_back(imagePoint2);
    vector<KeyPoint> keyPoint1, keyPoint2;
    keyPoint1 = keyPoints[0];
    keyPoint2 = keyPoints[1];
    for (int i = 0; i < GoodMatchPoints.size(); i++)
    {
        Points2f[1].push_back(keyPoint2[GoodMatchPoints[i].queryIdx].pt);
        Points2f[0].push_back(keyPoint1[GoodMatchPoints[i].trainIdx].pt);
    }
    Mat match;
    drawMatches(img1, keyPoint1, img2, keyPoint2, GoodMatchPoints, match);
    imshow("match", match);
    waitKey();

在调试时，OpenCV的内置函数drawMatches（）断言报了题目中的错，进过思考和查阅资料，原来是我的关键点矩阵没有对应上，想想自己大概也能理解错误的根源：矩阵运算中被乘矩阵的行列对应不上乘数矩阵的行列，也就是keyPoint1，keyPoint2用反了。所以将

drawMatches(img1, keyPoint1, img2, keyPoint2, GoodMatchPoints, match);

改为

drawMatches(img1, keyPoint2, img2, keyPoint1, GoodMatchPoints, match);

即可！