Pyramid architecture is a useful strategy to fuse multi-scale features in deep monocular depth estimation approaches. However, most pyramid networks fuse features only within the adjacent stages in a pyramid structure. To take full advantage of the pyramid structure, inspired by the success of DenseNet, this paper presents DCPNet, a densely connected pyramid network that fuses multi-scale features from multiple stages of the pyramid structure. DCPNet not only performs feature fusion between the adjacent stages, but also non-adjacent stages. To fuse these features, we design a simple and effective dense connection module (DCM). In addition, we offer a new consideration of the common upscale operation in our approach. We believe DCPNet offers a more efficient way to fuse features from multiple scales in a pyramid-like network. We perform extensive experiments using both outdoor and indoor benchmark datasets (i.e., the KITTI and the NYU Depth V2 datasets) and DCPNet achieves the state-of-the-art results.

Polar code is a kind of capacity-approaching code with explicit structure as part of the next generation wireless communication standard. The performance of the polar code is directly determined by the construction method, in which there are three important parameters: code rate (R), block-length (N), and design-SNR (DSNR). It is very difficult to obtain an optimal construction because all these three parameters should be optimized in a recursive structure model. In this paper, an efficient method, which constructs the desired optimal polar code by simultaneously selecting the three parameters in terms of the error probability, is presented. In the proposed construction, a dimensionality reduction search method is used to solve a fore mentioned optimization problem and to find the relation between the performance of polar code and design parameters. At the same time, the optimal parameters N and R can be obtained under any DSNR by taking the average group accuracy rate as the evaluation criterion. Through this method, the appropriate solution of three parameters in the construction of the polar code can be determined according to the required error probability. The proposed construction method is verified by numerical simulation, and the optimal performance to N, R and DSNR is compared and discussed.