This paper studies discrete-time attitude synchronization for a group of networked rigid bodies in three dimensions. The challenge is how to deal with 3-D motion dynamics on the Special Euclidean group: SE(3) in discrete-time fashion, and it is rigorously considered by employing exponential mapping. The rigid body network consisting of multiple rigid bodies with discrete-time dynamics and interconnection topology between them is first defined. Here, as the main feature of this work, it is shown that each attitude dynamics has passivity shortage. Attitude synchronization is next defined as the goal for the rigid body network, and
a novel distributed attitude synchronization law based on the passivity shortage is proposed. Convergence analysis is then provided, and simulation finally demonstrates validity of the present approach.