# Beyond the Flat Seafloor: A Closed-Form Two-View Constraint to Aid Sidescan Sonar Reconstruction

arXiv: https://arxiv.org/abs/2609.25271 · HTML: https://mlsanity.com/paper/2609.25271/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 3 of its 18 references that are in the map.
- First posted on arXiv 21 Sep 2026.

## Builds on (most cited first, 3 of 3)

- [NeuRSS: Enhancing AUV Localization and Bathymetric Mapping with Neural Rendering for Sidescan SLAM](https://mlsanity.com/paper/2405.05807/) (2024)
- [Neural Shape-from-Shading for Survey-Scale Self-Consistent Bathymetry from Sidescan](https://mlsanity.com/paper/2206.09276/) (2022)
- [Neural Network Normal Estimation and Bathymetry Reconstruction from Sidescan Sonar](https://mlsanity.com/paper/2206.07819/) (2022)

## Abstract (arXiv)

Sidescan sonar is a common sensor for both manned and autonomous marine exploration and mapping, yet very few methods build upon or exploit the geometric projection model of the sensor. As sidescan sonar is limited to a 1D range measurement, many approximations are frequently used, including the long-standing assumption of a flat seafloor. Rather than make similar approximations, this paper focuses on a multi-view geometry based approach and formalizes a two-view geometric constraint and proves that a shared feature is constrained to a locus within the intersection of a sphere and a plane. In addition, we characterize what governs the size of the ambiguity locus through Monte Carlo simulation that is grounded in real aperture and mounting geometry for both a surface vessel and an underwater vehicle. We translate additional simulations of relative trajectories for both vehicle platforms into concrete survey-planning guidance. Our results show that locus length is strongly governed by elevation misalignment, and peaks at a moderate oblique crossing angle of approximately 20 degrees, with minimal locus lengths obtained at near parallel and anti-parallel passes.