I have trouble in using Eigen3 Library along with OpenCV application in C++. I have installed Eigen3 library on my Ubuntu
First i would double check that the eigen include directions are found. You can use a CMakeList.txt to do so (and you should use the cmake functions to find headers and link to libraries instead of compiler flags)
Next you could try to remove the using namespaces
using namespace cv;
using namespace std;
using namespace Eigen;