Quantifying turbulence microstructure for improvement of underwater imaging

Sarah Woods; Weilin Hou; Wesley Goode; Ewa Jarosz; Alan Weidemann

doi:10.1117/12.887607

4 May 2011 Quantifying turbulence microstructure for improvement of underwater imaging

Sarah Woods, Weilin Hou, Wesley Goode, Ewa Jarosz, Alan Weidemann

Proceedings Volume 8030, Ocean Sensing and Monitoring III; 80300A (2011) https://doi.org/10.1117/12.887607
Event: SPIE Defense, Security, and Sensing, 2011, Orlando, Florida, United States

Abstract

Enhancing visibility through scattering media is important in many fields for gaining information from the scattering medium. In the ocean, in particular, enhancement of imaging and visibility is important for divers, navigation, robotics, and target and mine detection and classification. Light scattering from particulates and turbulence in the ocean strongly affects underwater visibility. The magnitude of this degrading effect depends upon the underwater environment, and can rapidly degrade the quality of underwater imaging under certain conditions. To facilitate study of the impact of turbulence upon underwater imaging and to check against our previously developed model, quantified observation of the image degradation concurrent with characterization of the turbulent flow is necessary, spanning a variety of turbulent strengths. Therefore, we present field measurements of turbulence microstructure from the July 2010 Skaneateles Optical Turbulence Exercise (SOTEX), during which images of a target were collected over a 5 m path length at various depths in the water column, concurrent with profiles of the turbulent strength, optical properties, temperature, and conductivity. Turbulence was characterized by the turbulent kinetic energy dissipation (TKED) and thermal dissipation (TD) rates, which were obtained using both a Rockland Scientific Vertical Microstructure Profiler (VMP) and a Nortek Vector velocimeter in combination with a PME CT sensor. While the two instrumental setups demonstrate reasonable agreement, some irregularities highlight the spatial and temporal variability of the turbulence field. Supplementary measurements with the Vector/CT in a controlled laboratory convective tank will shed additional light on the quantitative relationship between image degradation and turbulence strength.

Citation Download Citation

Sarah Woods, Weilin Hou, Wesley Goode, Ewa Jarosz, and Alan Weidemann "Quantifying turbulence microstructure for improvement of underwater imaging", Proc. SPIE 8030, Ocean Sensing and Monitoring III, 80300A (4 May 2011); https://doi.org/10.1117/12.887607

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