In this paper we address the benefit of adding adversarial training to the task of monocular depth estimation. A model can be trained in a self-supervised setting on stereo pairs of images, where depth (disparities) are an intermediate result in a right-to-left image reconstruction pipeline. For the quality of the image reconstruction and disparity prediction, a combination of different losses is used, including L1 image reconstruction losses and left-right disparity smoothness. These are local pixel-wise losses, while depth prediction requires global consistency. Therefore, we extend the self-supervised network to become a Generative Adversarial Network (GAN), by including a discriminator which should tell apart reconstructed (fake) images from real images. We evaluate Vanilla GANs, LSGANs and Wasserstein GANs in combination with different pixel-wise reconstruction losses. Based on extensive experimental evaluation, we conclude that adversarial training is beneficial if and only if the reconstruction loss is not too constrained. Even though adversarial training seems promising because it promotes global consistency, non-adversarial training outperforms (or is on par with) any method trained with a GAN when a constrained reconstruction loss is used in combination with batch normalisation. Based on the insights of our experimental evaluation we obtain state-of-the art monocular depth estimation results by using batch normalisation and different output scales.

本研究探讨了将对抗性训练应用于单目深度估计任务中的益处，并扩展了自监督网络以成为生成对抗网络（GAN）来实现全局一致性。通过对不同像素级重构损失结合Vanilla GAN， LSGAN和Wasserstein GAN等进行广泛的实验评估，得出当重构损失不太受限制时，对抗训练是有益的结论，并证明在使用批量归一化时，无需使用GAN的非对抗性训练法表现优异。因此，我们采用批量规范化和不同的输出比例，获得了最新的单目深度估计结果。

对单目深度估计采用对抗性训练的益处