Surface Normal Data Guided Depth Recovery with Graph Laplacian Regularization

High-quality depth information has been increasingly used in many real-world multimedia applications in recent years. Due to the limitation of depth sensor and sensing technology, actually, the captured depth map usually has low resolution and black holes. In this paper, inspired by the geometric relationship between surface normal of a 3D scene and their distance from camera, we discover that surface normal map can provide more spatial geometric constraints for depth map reconstruction, as depth map is a special image with spatial information, which we called 2.5D image. To exploit this property, we propose a novel surface normal data guided depth recovery method, which uses surface normal data and observed depth value to estimate missing or interpolated depth values. Moreover, to preserve the inherent piecewise smooth characteristic of depth maps, graph Laplacian prior is applied to regularize the inverse problem of depth maps recovery and a graph Laplacian regularizer(GLR) is proposed. Finally, the spatial geometric constraint and graph Laplacian regularization are integrated into a unified optimization framework, which can be efficiently solved by conjugate gradient(CG). Extensive quantitative and qualitative evaluations compared with state-of-the-art schemes show the effectiveness and superiority of our method.