Estimating depth from a monocular image has become a very popular task in computer vision for identifying important geometric information of the scene. While its performance has been significantly improved by convolutional neural networks (CNNs) in recent years, depth-estimation accuracy is still unsatisfactory at locations with abrupt depth changes. This is mainly caused by the use of spatially consistent filters in CNNs which directly mix the features of different objects when applied to the pixels near the object borders. Moreover, the performance gap between depth estimation from single image and that from a stereo pair remains quite large due to the ill-posed nature of the former one. In this paper, we propose a new depth-aware convolutional neural network (DACNN) to address these issues. We first design a novel depth-aware convolution operation for DACNN, that can adaptively choose subsets of relevant features for convolutions at each location. Specifically, we compute hierarchical depth features as the guidance, and then estimate the depth map using such depth-aware convolution which can leverage the guidance to adapt the filters. In addition, we also introduce a pre-trained stereo network into DACNN as the teacher to carry out knowledge distillation on the student monocular network with a specially designed loss function. Experimental results on the KITTI online benchmark and Eigen split datasets show that the proposed method achieves the state-of-the-art performance for single-image depth estimation.

The accuracy of stereo matching has been greatly improved by using deep learning with convolutional neural networks. To further capture the details of disparity maps, in this paper, we propose a novel semantic stereo network named SSPCV-Net, which includes newly designed pyramid cost volumes for describing semantic and spatial information on multiple levels. The semantic features are inferred by a semantic segmentation subnetwork while the spatial features are derived by hierarchical spatial pooling. In the end, we design a 3D multi-cost aggregation module to integrate the extracted multilevel features and perform regression for accurate disparity maps. We conduct comprehensive experiments and comparisons with some recent stereo matching networks on Scene Flow, KITTI 2015 and 2012, and Cityscapes benchmark datasets, and the results show that the proposed SSPCV-Net significantly promotes the state-of-the-art stereo-matching performance.

Depth estimation from monocular videos has important applications in many areas such as autonomous driving and robot navigation. It is a very challenging problem without knowing the camera pose since errors in camera-pose estimation can significantly affect the video-based depth estimation accuracy. In this paper, we present a novel SC-GAN network with end-to-end adversarial training for depth estimation from monocular videos without estimating the camera pose and pose change over time. To exploit cross-frame relations, SC-GAN includes a spatial correspondence module which uses Smolyak sparse grids to efficiently match the features across adjacent frames, and an attention mechanism to learn the importance of features in different directions. Furthermore, the generator in SC-GAN learns to estimate depth from the input frames, while the discriminator learns to distinguish between the ground-truth and estimated depth map for the reference frame. Experiments on the KITTI and Cityscapes datasets show that the proposed SC-GAN can achieve much more accurate depth maps than many existing state-of-the-art methods on monocular videos.