1. A method for three-dimensional video coding, the method comprising: receiving input data associated with a current depth region of a depth map in a given view; identifying a co-located texture region of a texture picture corresponding to the depth map in the given view; determining whether the co-located texture region has unknown or invalid motion data, wherein the co-located texture region has unknown or invalid motion data if the co-located texture region of the texture picture or any texture sub-region in the co-located texture region is Intra-coded or a corresponding reference index is invalid; responsive to the co-located texture region having unknown or invalid motion data, determining first motion information for the current depth region by setting the first motion information for the current depth region to pre-defined motion information or to motion information derived based on a neighboring texture region, and responsive to the co-located texture region having valid motion data, determining the first motion information for the current depth region depending on second motion information associated with the co-located texture region; and applying coding or decoding to the input data associated with the current depth region using the first motion information.