  In this paper, we present a novel indoor 3D reconstruction method with
occluded surface completion, given a sequence of depth readings. Prior
state-of-the-art (SOTA) methods only focus on the reconstruction of the visible
areas in a scene, neglecting the invisible areas due to the occlusions, e.g.,
the contact surface between furniture, occluded wall and floor. Our method
tackles the task of completing the occluded scene surfaces, resulting in a
complete 3D scene mesh. The core idea of our method is learning 3D geometry
prior from various complete scenes to infer the occluded geometry of an unseen
scene from solely depth measurements. We design a coarse-fine hierarchical
octree representation coupled with a dual-decoder architecture, i.e.,
Geo-decoder and 3D Inpainter, which jointly reconstructs the complete 3D scene
geometry. The Geo-decoder with detailed representation at fine levels is
optimized online for each scene to reconstruct visible surfaces. The 3D
Inpainter with abstract representation at coarse levels is trained offline
using various scenes to complete occluded surfaces. As a result, while the
Geo-decoder is specialized for an individual scene, the 3D Inpainter can be
generally applied across different scenes. We evaluate the proposed method on
the 3D Completed Room Scene (3D-CRS) and iTHOR datasets, significantly
outperforming the SOTA methods by a gain of 16.8% and 24.2% in terms of the
completeness of 3D reconstruction. 3D-CRS dataset including a complete 3D mesh
of each scene is provided at project webpage.
