3D Visual Communications

5.7 Layered Depth Video (LDV)

Although MVD can synthesize any infinitely dense intermediate views with high fidelity from a limited number of sparse views transmitted through the network, the overall required bandwidth to convey all the color and depth information of the N views (including central and side views) is still comparatively large, even bringing in the MVC coding for color and depth information. To further reduce the bit rate, one could deploy conventional video coding on the central view only; apply view synthesis technologies on the decoded and reconstructed central view to generate other N − 1 side views; and take the difference between the projection and the neighboring camera result as residual information. The residual consists of disoccluded information and is therefore mainly concentrated along depth discontinuities of foreground objects as well as image boundary data in both side views. The overall bit stream consists of three major components: (1) complete color and depth information from the central view; (2) parameters for view synthesis, such as geometry parameters for camera and real-world depth range; and (3) residual of color and depth information in the side views. At the decoder side, as shown in Figure 5.21, the decoder will first reconstruct the central view once having received the bit stream. Then, the decoder projects the central camera view into the other neighboring views using the view synthesis parameters to synthesize side views. The residual ...