Visualization for multi-static underwater LLS system using Image Based Rendering

Abstract

Over the last several decades developments in Underwater Laser Line Scan (LLS) systems have resulted in significant improvements in turbid water imaging performance. In addition to allowing for high quality image acquisition through tens of attenuation lengths, the recently renewed interest in multiple platform distributed LLS configurations also has the potential for synoptic coverage of much larger regions of seabed. A related issue worth investigation is how to utilize these capabilities to improve rendering of the underwater scenes. In this regard, Light Field Rendering (LFR) - a type of Image Based Rendering (IBR) technique offers several advantages. LFR enables multi-perspective target visualization without measuring the geometrical dimension of the target. Compared to other IBR techniques, LFR can provide Signal-to-Noise Ratio (SNR) improvements and the ability to image through obscuring objects in front of the target. On the other hand, multi-static LLS can be readily configured to acquired images to generate LFR. This paper investigates the application of LFR to images taken from a distributed bi-static LLS imager to create multi-perspective rendering of an unknown underwater scene. The issues related to effectively applying this technique to underwater LLS imagery are analyzed and image post-processing flow to addresses these issues are proposed. An experiment was conducted in FAU-HBOI optical imaging test tank, the results from which demonstrated the capability of using bi-static/multi-static LLS system to generated LFR and also verified the proposed image processing flow. The aforementioned benefits of LFR were also presented.