1. Apparatus for coding a bit stream representing a three-dimensional video comprising a sequence of views, wherein a depth map is associated to each view, the depth map comprising depth information of the view with respect to a position to the camera capturing the view, the apparatus comprising: a partitioner for partitioning the depth map into coding units; a determiner for determining a type of model function for each coding unit based on the depth information of the coding unit; a reducer for reducing the coding unit to single residual value for each segment generated by the model function; and a signaler for signaling the model function used and the residual value into the bitstream.