CODEWITHSUNDEEP
c++opencveigeneigen3
StereoMatching
StereoMatching

Reputation: 5019

Convert the cv::Mat of OpenCV to Eigen

This post show us how to map the cv::Mat to Eigen matrix without copy the data, it works fine, but there are one thing I do not understand.

Mat A(20, 20, CV_32FC1);
cv::randn(A, 0.0f, 1.0f); // random data

// Map the OpenCV matrix with Eigen:
Eigen::Map<Eigen::Matrix<float, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor>> A_Eigen(A.ptr<float>(), A.rows, A.cols);

The problem is, the Mat A do not tell the A_Eigen how many bytes per row it should take, as far as I know the cv::Mat of OpenCV may or may not do padding on each row, do I need to tell the Eigen how many bytes per row (how?)?, or I can safely omit it?

Ps: I am using Eigen 3

Upvotes: 0

Views: 1545

Answers (1)

Avi Ginsburg
Avi Ginsburg

Reputation: 10596

Instead of using A.cols, use A.step (or A.step[0] or A.step[1]?). If the OpenCV matrix is not continuous, then m.step != m.cols*m.elemSize(). You'll just have to ignore any additional columns, e.g. with A_Eigen.block<0,0>(A.rows, A.cols).

Upvotes: 1

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