Current methods for single-image depth estimation use training datasets with
real image-depth pairs or stereo pairs, which are not easy to acquire. We
propose a framework, trained on synthetic image-depth pairs and unpaired real
images, that comprises an image translation network for enhancing realism of
input images, followed by a depth prediction network. A key idea is having the
first network act as a wide-spectrum input translator, taking in either
synthetic or real images, and ideally producing minimally modified realistic
images. This is done via a reconstruction loss when the training input is real,
and GAN loss when synthetic, removing the need for heuristic
self-regularization. The second network is trained on a task loss for synthetic
image-depth pairs, with extra GAN loss to unify real and synthetic feature
distributions. Importantly, the framework can be trained end-to-end, leading to
good results, even surpassing early deep-learning methods that use real paired
data.

本文提出一种基于图像翻译网络和深度预测网络的框架，使用合成的图像 - 深度对和非配对的真实图像进行训练，实现单图深度估计。该框架可以端到端训练，得到好的结果，甚至超过使用真实配对数据的早期深度学习方法。