Generation of High‐resolution Three‐dimensional Reconstructions of the Seafloor in Color using a Single Camera and Structured Light

Abstract

Visual maps of the seafloor can provide objective information to characterize benthic ecosystems and survey the distribution of mineral deposits on spatial scales that cannot be otherwise assessed. This paper proposes a threedimensional mapping method based on light sectioning that enables the simultaneous capture of both structure and color from the images of a single camera. The advantages of the method include high and consistent resolution of the bathymetry, and the simplicity of the setup and the algorithm used to process the data it obtains. The hardware requirements for collecting the data are a single camera, a line laser, and a light, making it possible to deploy the mapping device along with other sensors and devices on underwater platforms such as autonomous underwater vehicles and remotely operated vehicles that can log navigation data. The system has been deployed on a total of 11 cruises, among others, to survey manganese-rich crust deposits on the slopes of Takuyo #5 seamount in the Pacific at depths of more than 2,000 m. In this paper, we present the data that were obtained on one of these cruises.

Methods for quantitative studies of seafloor hydrothermal systems using 3D visual reconstructions

“…This study overcomes these technical challenges and realises such a system by extension of the long-baseline structured light and colour mapping algorithm described in [4] to use imagery from a separate, high-sensitivity colour camera synchronised with a highpower strobe. This extension allows us to achieve centimetre order resolution 3D bathymetric measurements and retain colour information through the use of the strobed images taken from significantly higher altitudes than was previously possible (10 m instead of 2 m).…”

“…3D colour reconstructions of the seafloor have been generated using the mapping algorithm described in [4], that has been adapted for long range mapping using multiple synchronised flashes and a high power sheet laser for seafloor illumination and bathymetric measurements, respectively.…”

“…1, is based on laser profiling extended to use colour. In this study, we extend the method described in our previous work [4] in order to achieve mapping from significantly higher altitudes than was previously possible. In our previous work, the algorithm assumed a single camera to capture both the laser line projection and the illuminated area of the seafloor.…”

“…Visual mapping of the seafloor is a versatile tool for underwater research with applications including benthic habitat mapping [1][2][3], survey of mineral resources [4], and mapping of archaeological sites [5]. In particular, the 3D imaging techniques developed in recent years can generate high resolution digital reconstructions of the seafloor [3,4,6,7].…”

“…In particular, the 3D imaging techniques developed in recent years can generate high resolution digital reconstructions of the seafloor [3,4,6,7]. The addition of colour information enhances the representation of the seafloor compared to conventional bathymetric mapping techniques, and potentially allows for a greater diversity of classification and statistical analysis of features of interest.…”