如何从opencv cv :: Mat或行优先的数组初始化本征矩阵？ [英] how to initialize a Eigen Matrix from an opencv cv::Mat, or from an array which is row-major?

问题描述

我发现Eigen的Matrix是默认的以列为主的矩阵，类似于MATLAB，但是如何从cv :: Mat初始化Eigen :: MatrixXd？以下代码是我的测试。但是它们都无法成功编译。有人可以给我一些建议吗？或其他一些链接？

I found that Eigen's Matrix is default column-major, which is like MATLAB, but how do I initialize an Eigen::MatrixXd from an cv::Mat? The following code is my test. But none of them could be compiled successfully. Could someone give me some advice, please? or some other links? Thanks.

    cv::Mat A_M=cv::Mat(rows, cols, CV_64FC1);
    double *A=(double *)A_M.data();
    typedef Map<MatrixXd> MapMat;
    MapMat A_eigen(A,m,n);

    Eigen::Matrix<double,Eigen::Dynamic,Eigen::Dynamic,Eigen::RowMajor> A_eigen;
    Eigen::Map<Matrix<double,Eigen::Dynamic,Eigen::Dynamic,Eigen::RowMajor> >(A,m,n) = A_eigen;

已更新：

    double *A=(double *)A_M.data();//m*n
    double *B=(double *)B_M.data();//n*p
    double *C=(double *)C_M.data();//m*p
    //regular Eigen Matrix
    Eigen::MatrixXd A_eigenMat;
    Eigen::MatrixXd B_eigenMat;
    Eigen::MatrixXd C_eigenMat;
    Eigen::Map<Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor> > A_mappedMat (A, m, n);
    Eigen::Map<Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor> > B_mappedMat (B, n, p);
    Eigen::Map<Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor> > C_mappedMat (C, m, p);
    // Eigen handles the conversion from row major to column major
    A_eigenMat = A_mappedMat;
    B_eigenMat = B_mappedMat;
    C_eigenMat = C_mappedMat;

    // multiplication
    C_eigenMat=A_eigenMat*B_eigenMat;

然后，当我输出M_C时，其结果是错误的。似乎C_eigenMat没有将数据复制到M_C.data中。

Then, when I output the M_C, its result is wrong. It seems the C_eigenMat didn't copy the data into M_C.data.

推荐答案

来自 OpenCV和Eigen之间的转换：

cv::Mat_<float> a = Mat_<float>::ones(2,2);
Eigen::Matrix<float,Dynamic,Dynamic> b;
cv2eigen(a,b);

已经被回答在SO上：

//allocate memory for a 4x4 float matrix
cv::Mat cvT(4,4,CV_32FC1); 

//directly use the buffer allocated by OpenCV
Eigen::Map<Matrix4f> eigenT( cvT.data() ); 

以及另外一个 SO发布

这篇关于如何从opencv cv :: Mat或行优先的数组初始化本征矩阵？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！