Direct estimation of deformable motion parameters from range image sequence

A method is described for estimating range flow (space displacement vector field) on a nonrigid object as well as a rigid object from a sequence of range images. The method can directly estimate the deformable motion parameters by solving a system of linear equations which are obtained by substituting a linear transformation of a nonrigid object expressed by a Jacobian matrix into motion constraints based on an extension of the conventional scheme used in intensity image sequences, and the range flow is obtained from the motion parameters and linear transformation. The algorithm is supported by experiments of motion estimation of a sheet of paper, a piece of cloth, the movement of human skin, and the motion of a rubber balloon being inflated using real range image sequences acquired by a video rate range finder. Furthermore, it is shown that by adding the intensity image sequence to the range information, one can prevent the equation system from falling in an ill-posed condition