1. A computer-implemented method to determine absolute rotations, the method comprising: obtaining, by one or more computing devices, a relative rotation estimates matrix that includes a plurality of relative rotation estimates, wherein each of the plurality of relative rotation estimates is an estimate of a relative rotation between attitudes of two of a plurality of local reference frames; determining, by the one or more computing devices, values for a low-rank matrix that result in a desirable value of a cost function that is based on a low-rank and sparse matrix decomposition of the relative rotation estimates matrix, the cost function including the low-rank matrix and a sparse matrix that is nonzero in correspondence of one or more outliers of the plurality of relative rotation estimates; and determining, by the one or more computing devices, an absolute rotations matrix that includes a plurality of absolute rotations based at least in part on the values of the low-rank matrix that result in the desirable value of the cost function, wherein each of the plurality of absolute rotations is a rotation between the attitude of one of the local reference frames and a global reference frame.