Self-Supervised Depth Estimation in Laparoscopic Image using 3D Geometric Consistency

TL;DR

This paper introduces M3Depth, a self-supervised depth estimation method for laparoscopic images that leverages 3D geometric consistency in stereo pairs, improving accuracy over previous approaches without requiring ground truth depth.

Contribution

The paper proposes a novel self-supervised depth estimator that utilizes 3D geometric structural information in stereo images, enhancing depth accuracy in laparoscopic imaging.

Findings

Outperforms previous self-supervised methods on public and new datasets

Demonstrates strong generalization across different laparoscopes

Effectively handles border regions to improve correspondence accuracy

Abstract

Depth estimation is a crucial step for image-guided intervention in robotic surgery and laparoscopic imaging system. Since per-pixel depth ground truth is difficult to acquire for laparoscopic image data, it is rarely possible to apply supervised depth estimation to surgical applications. As an alternative, self-supervised methods have been introduced to train depth estimators using only synchronized stereo image pairs. However, most recent work focused on the left-right consistency in 2D and ignored valuable inherent 3D information on the object in real world coordinates, meaning that the left-right 3D geometric structural consistency is not fully utilized. To overcome this limitation, we present M3Depth, a self-supervised depth estimator to leverage 3D geometric structural information hidden in stereo pairs while keeping monocular inference. The method also removes the influence of border regions unseen in at least one of the stereo images via masking, to enhance the correspondences between left and right images in overlapping areas. Intensive experiments show that our method outperforms previous self-supervised approaches on both a public dataset and a newly acquired dataset by a large margin, indicating a good generalization across different samples and laparoscopes. Code and data are available at https://github.com/br0202/M3Depth.