PackNet-SfM: 3D Packing for Self-Supervised Monocular Depth Estimation

Densely estimating the depth of a scene from a single image is an ill-posed inverse problem that is seeing exciting progress with self-supervision from strong geometric cues, in particular from training using stereo imagery. In this work, we investigate the more challenging structure-from-motion (SfM) setting, learning purely from monocular videos. We propose PackNet - a novel deep architecture that leverages new 3D packing and unpacking blocks to effectively capture fine details in monocular depth map predictions. Additionally, we propose a novel velocity supervision loss that allows our model to predict metrically accurate depths, thus alleviating the need for test-time ground-truth scaling. We show that our proposed scale-aware architecture achieves state-of-the-art results on the KITTI benchmark, significantly improving upon any approach trained on monocular video, and even achieves competitive performance to stereo-trained methods.