This tool allows an easy visualization of arbitrary spatial rotations (rotation matrices in SO(3)) specified in any of the common conventions, like yaw-pitch-roll, quaternions, axis-angle, or just the 3x3 matrices.
For a technical discussion of the different conventions and the formulas to convert between them, please refere to the technical report "A tutorial on SE(3) transformation parameterizations and on-manifold optimization" (arXiv).