Development of inference methods for rotational motions on ground surface

In this study, we develop two methods for the inference of rotation vector on ground surface, two rocking rotations and a single torsional rotation. The first, termed nth-order elastic method, is based on the elasticity of the ground surface. The rotation vector is constructed from the first derivative with respect to the space of the ground surface motions. The first derivative is calculated from simultaneous equations by n-th order Taylor expansion obtained by difference motion between multiple observation points. Meanwhile, the second, termed rigid method, is based on the rigidity of ground surface and the rotation.