טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSpier Ori
SubjectIn-Situ Target-less Calibration of a Turbid Media
DepartmentDepartment of Electrical Engineering
Supervisors Dr. Guy Gilboa
Dr. Avital Treibitz
Full Thesis textFull thesis text - English Version


Abstract

More than 70% of the Earth's surface is covered by water, yet only a small part of it has been explored (5% according to NOAA). Optical imaging, so fundamental to scientific research and human activities, is very challenging underwater, and different from what we, as humans, are used to handling. This research seeks to enhance underwater imaging capabilities, in order to promote oceanic based research and activities.

The color of an object imaged in a turbid medium varies with distance and medium properties, rendering color an unstable source of information. Assuming that 3D scene structure has become relatively easy to estimate, the main challenge in color recovery is calibrating medium properties in situ, at the time of acquisition. Existing attenuation calibration methods use either color charts, external hardware, or multiple images of an object. Here we show that none of these is needed for calibration.

This research proposes a method for estimating the medium optical properties (both attenuation and scattering) using only images of backscattered light from the light sources of the system. This is advantageous in turbid media where the object signal is noisy, and also alleviates the need for correspondence matching in the calibration phase, which can be difficult in high turbidity.

We demonstrate the advantages of our method through simulations and real-life experiments at sea. The research work included simulations, lab setup design and experiments, sea setup design and scuba diving experiments.