1. A method for depth coding in a three-dimensional video coding system, the method comprising: receiving input data associated with a current depth block of a depth map in a given view, wherein the current depth block is corresponding to a texture collocated block of a texture picture in the given view; selecting one of a plurality of texture collocated sub-blocks within the texture collocated block and identifying whether the selected texture collocated sub-block is valid or not; determining first motion information associated with the texture collocated block, wherein the first motion information associated with the texture collocated block corresponds to second motion information of the selected texture collocated sub-block corresponding to the texture collocated block when the selected texture collocated sub-block is identified as valid; deriving a Merge candidate, or a motion vector predictor (MVP) or disparity vector predictor (DVP) candidate from a candidate list, wherein the candidate list includes a texture candidate derived from the first motion information associated with the texture collocated block; and applying coding or decoding to the input data associated with the current depth block using the texture candidate if the texture candidate is selected as the Merge candidate in Merge mode, or the texture candidate is selected as the MVP or DVP candidate in Inter mode based on advanced motion vector prediction (AMVP), wherein the selected texture collocated sub-block is not valid if: the selected texture collocated sub-block is Intra-coded; a reference picture of the selected texture collocated sub-block does not have a corresponding depth picture in a current view; or a corresponding depth picture in the current view is not available.