EndoMetric: Near-Light Monocular Metric Scale Estimation in Endoscopy

TL;DR

This paper introduces a novel model-based method to accurately estimate the real-world scale of 3D reconstructions in monocular endoscopy by utilizing near-light sources and light attenuation laws, enabling precise medical measurements.

Contribution

It presents the first approach to recover metric scale in monocular endoscopy without learned priors, using embedded near-light sources and physical light laws.

Findings

Successfully estimates metric scale in endoscopic images

Enables conversion of endoscopes into metric measurement devices

Improves accuracy of 3D reconstructions in medical applications

Abstract

Geometric reconstruction and SLAM with endoscopic images have advanced significantly in recent years. In most medical fields, monocular endoscopes are employed, and the algorithms used are typically adaptations of those designed for external environments, resulting in 3D reconstructions with an unknown scale factor. For the first time, we propose a method to estimate the real metric scale of a 3D reconstruction from standard monocular endoscopic images without relying on application-specific learned priors. Our fully model-based approach leverages the near-light sources embedded in endoscopes, positioned at a small but nonzero baseline from the camera, in combination with the inverse-square law of light attenuation, to accurately recover the metric scale from scratch. This enables the transformation of any endoscope into a metric device, which is crucial for applications such as measuring polyps, stenosis, or assessing the extent of diseased tissue.