A Calibration Tool for Refractive Underwater Vision

TL;DR

This paper introduces the first open-source calibration toolbox for underwater cameras, enabling accurate refractive calibration of vision systems with various port types through comprehensive end-to-end procedures.

Contribution

It provides a novel, open-source solution for underwater refractive camera calibration, addressing a gap in existing tools for systems with different port geometries.

Findings

Verified with rendered datasets

Validated through real-world experiments

Supports calibration of stereo and housing systems

Abstract

Many underwater applications rely on vision sensors and require proper camera calibration, i.e. knowing the incoming light ray for each pixel in the image. While for the ideal pinhole camera model all viewing rays intersect in a single 3D point, underwater cameras suffer from - possibly multiple - refractions of light rays at the interfaces of water, glass and air. These changes of direction depend on the position and orientation of the camera inside the water-proof housing, as well as on the shape and properties of the optical window, the port, itself. In recent years explicit models for underwater vision behind common ports such as flat or dome port have been proposed, but the underwater community is still lacking a calibration tool which can determine port parameters through refractive calibration. With this work we provide the first open source implementation of an underwater refractive camera calibration toolbox. It allows end-to-end calibration of underwater vision systems, including camera, stereo and housing calibration for systems with dome or flat ports. The implementation is verified using rendered datasets and real-world experiments.