Title: UniVDC: A Zero-Shot Unified Diffusion Framework for Consistent Video Depth Completion
Primary area: applications to computer vision, audio, language, and other modalities
Keywords: 3D Perception, Video Diffusion Model, Depth completion

Abstract: Recovering metrically consistent and temporally stable depth from dynamic videos remains challenging, particularly when sparse, noisy measurements coexist with structural voids, occlusion reveals, motion drift, and sensor dropouts. Under these conditions, single-frame methods lack temporal correction while existing video depth estimation approaches underutilize explicit sparse geometry, leading to scale drift and flicker. To address this, we introduce UniVDC, the first unified zero-shot spatiotemporal diffusion framework for long-range video depth completion. Our approach centers on multi-source geometric and semantic priors. We combine two geometric inputs: fine-grained relative depth with structural and edge cues from a depth estimator, and coarse metric depth obtained by inverse-distance–weighted interpolation of sparse measurements. Unlike methods that feed RGB frames directly, we extract global semantic features and inject them hierarchically into the diffusion network, yielding compact geometric inputs and scene context robust to frame-level appearance noise. A four-stage training protocol stabilizes prior fusion and calibrates the long-horizon scale. In inference, we introduce bidirectional overlapping sliding-window (BOSW) to reduce scale drift and boundary error accumulation over long sequences and alleviate occlusion in one-directional inference. Experiments show that UniVDC achieves state-of-the-art performance on multiple zero-shot video depth completion benchmarks in terms of completion accuracy, structural consistency, and temporal coherence.