How to convert from Eigen::Affine3f to Eigen::Matrix4f

Question

I have two questions.

1. Does the rigid transformation represented in Eigen::Affine3f and Eigen::Matrix4f will be the same ?

2. How can we convert from Eigen::Affine3f to Eigen::Matrix4f and vice versa ?

Thanks for your help!

Answer 1

Yes, internally an Affine3f stores a MatrixXf, so you can do:

Eigen::Affine3f A;
Eigen::Matrix4f M;
M = A.matrix();
A = M;               // assume that M.row(3) == [0 0 0 1]