Get Rotation Matrix from 2 Orthogonal Planes

Shows a 3D point cloud and lets the user select a plane by clicking on two points. The selected plane is highlighted.

The math is pretty simple:

A surface normal is computed for each plane using eigenvectors, later the y axis is set to be 0, any rotation is subtracted from it to obtain orthogonals surface normals. The cross product ot them is computed to obtan the z axis normal and conform the 3x3 rotation matrix.