Obtaining accurate depth measurements out of a single image represents a
fascinating solution to 3D sensing. CNNs led to considerable improvements in
this field, and recent trends replaced the need for ground-truth labels with
geometry-guided image reconstruction signals enabling unsupervised training.
Currently, for this purpose, state-of-the-art techniques rely on images
acquired with a binocular stereo rig to predict inverse depth (i.e., disparity)
according to the aforementioned supervision principle. However, these methods
suffer from well-known problems near occlusions, left image border, etc
inherited from the stereo setup. Therefore, in this paper, we tackle these
issues by moving to a trinocular domain for training. Assuming the central
image as the reference, we train a CNN to infer disparity representations
pairing such image with frames on its left and right side. This strategy allows
obtaining depth maps not affected by typical stereo artifacts. Moreover, being
trinocular datasets seldom available, we introduce a novel interleaved training
procedure enabling to enforce the trinocular assumption outlined from current
binocular datasets. Exhaustive experimental results on the KITTI dataset
confirm that our proposal outperforms state-of-the-art methods for unsupervised
monocular depth estimation trained on binocular stereo pairs as well as any
known methods relying on other cues.

该论文提出了一种可以使用无标注数据进行训练的，基于三目摄像机的深度估计方法，其在 KITTI 数据集上取得了比其他基于双目摄像机以及其他线索的方法更好的性能。