Convert from std::vector

I have std::vector in C++ which represents voxels in x,y,z dimensions each cv::Mat in the vector is a cross section or a slice of the volume. Unfortunately OpenCV doesn't offer any wrapper to this data type, so I decided to use non-supported module from Eigen library called Tensor. I cannot see any constructor in the documentation that would allow me efficient conversion from vector of cv::Mat to eigen tensor without the need to reallocate data.

What is the most efficient way to convert from std::vector to Eigen::Tensor