Seeing Down the Line: Endoscopic Reconstruction with Centerline Constraints

Andrea Dunn Beltran, Romain Hardy, Pranav Rajpurkar

Keywords: 3D reconstruction, SLAM, Endoscopy

TL;DR: We add a lightweight centerline-based coordinate layer to a standard 3D Gaussian mapper, matching EndoGSLAM’s geometry at near-MonoGS speed while providing online colon coverage maps for free.

Abstract: Colonoscopy remains the gold standard for colorectal cancer screening, but there is still no real-time, geometry-aware way to quantify which parts of the colon have been inspected during a procedure. We revisit 3D Gaussian endoscopic reconstruction as a representation and geometry problem rather than a new network design. Assuming known camera poses and off-the-shelf depth or photometric supervision, we add a simple centerline-based coordinate system and priors on top of an existing Gaussian mapping backbone. From the noisy pose stream we maintain an online centerline and Bishop frame, assign each Gaussian tubular coordinates, and use these coordinates both to regularize the map toward a hollow tube and to accumulate coverage statistics in colon-intrinsic space. On long C3VD phantom colonoscopy sequences, this lightweight modification achieves Chamfer distance comparable to or better than an endoscopy-specific 3D Gaussian SLAM baseline while running at frame rates close to MonoGS and yielding improved rendering quality, with negligible additional computation. At the same time, the same representation produces unrolled colon views and segment-wise coverage summaries essentially "for free", making centerline-aware Gaussian mapping a practical drop-in component for future real-time quality monitoring tools in colonoscopy.

Primary Subject Area: Image Acquisition and Reconstruction

Secondary Subject Area: Application: Endoscopy

Registration Requirement: Yes

Visa & Travel: No

Read CFP & Author Instructions: Yes

Originality Policy: Yes

Single-blind & Not Under Review Elsewhere: Yes

LLM Policy: Yes

Submission Number: 33