Intra coding for depth maps using adaptive boundary location

Depth maps, an essential part in the new generation of 3D video coding, allow rendering of arbitrary viewpoints of a video scene. Depth maps are characterized by sharp object boundaries, which significantly affect the rendering quality and account for the most bitrate for depth map coding. This paper proposes a novel intra coding method for depth maps based on a two-step adaptive boundary location process. By extracting a series of sub-blocks along a depth boundary and refining the boundary within sub-blocks, accurate predictions for blocks with arbitrary edge shapes can be realized. Experimental results show that the proposed scheme achieves bitrate reductions of up to 28% and 13% on average for seven test sequences of MPEG 3DV compared to original intra coding of H.264/AVC considering the same quality of synthesized views. Besides, subjective quality of virtual views is improved owning to well preserved boundary information.