May 3, 2012

Georges Bank seafloor image processing. Brown Bag Lunch with Seth Newburg and Michael Soroka: AUV Lab, MIT Sea Grant

Date: Tuesday, May 29, 2012
Time: 12:00 - 1:00 pm
Location: MIT E38-300 (292 Main St., Cambridge, 3rd floor)

Bring your lunch and learn about monitoring for invasive species with a MITSG autonomous underwater vehicle

An aggressively growing sea squirt, Didemnum vexillum, is found growing on Georges Bank and throughout coastal subtidal areas from Connecticut to Maine. The sea squirt grows over sessile organisms and often is the most abundant species in the community where it is found. On Georges Bank it may impact fisheries by restricting groundfish feeding (Valentine, et al. 2007) and threaten the scallop fishery by preventing scallop settlement (Morris, et al. 2009).

In order to document impacts and predict dispersion and distribution of Didemnum, we need to quickly survey the sea floor. To date, only a small portion of Georges Bank has been surveyed using cameras and videos. A system is needed that can cover a large area and identify potential Didemnum infestations in order to document the scope of the invasion. Autonomous underwater vehicles (AUVs) offer a platform for testing sensors, comparing the records to digital images, and collecting samples for verification.

Capable of untethered dives, the Odyssey IV AUV collects high resolution images from 1 m altitude off the sea floor. A CTD sonde mounted on the vehicle collects environmental data, which is time stamped and stored in an onboard database with the images. The Odyssey IV cruises at speeds up to 1.4 m/s and hovers using vectored thrusters. The Odyssey IV AUV is a valuable tool for surveying and detecting the presence of Didemnum at low cost and without causing damage to the benthic habitat.

Some of the first deployments of the Odyssey IV were to perform bottom-imaging surveys on Georges Bank, and 2700 images of the seafloor were captured. These image sets revealed the presence of Didemnum, however, photographs made by the deep water imaging system lack the contrast and color fidelity needed to accurately identify and study the marine organisms. Image processing algorithms were developed and used to compensate for imaging artifacts and enhance the photographs in order to reveal the biodiversity in this marine habitat. It was found that creating mosaics of overlapping photographs using the SIFT-RANSAC method (Brown and Lowe, 2007) is helpful in collecting census data of the benthic community.

About Seth Newburg
Seth Newburg has been a research engineer in the MIT AUV Lab since March 2009. His interests focused on underwater robotics technology ten years earlier while an undergraduate at MIT when he founded Project ORCA, a student team dedicated to designing AUVs for the International Autonomous Underwater Vehicles Competition sponsored by AUVSI and ONR. The experience implementing sonar systems for AUVs led him to pursue research in auditory physiology, including that of whales and dolphins, for his doctorate in biomedical engineering at Boston University. As part of the AUV Lab's engineering team, Newburg draws on his interdisciplinary background in carrying out his primary responsibility for the design and integration of robust sensor systems for the Odyssey IV autonomous underwater vehicle project.

About Michael Soroka
Mike Soroka is a Research Engineer at the MIT Sea Grant AUV laboratory specializing in mechanical engineering and mechatronics. He has been a member of the AUV lab for three years, over the course of which he has helped develop the Odyssey IV deep ocean AUV, and has operated the Odyssey IV in the field collecting oceanographic and marine science data. Soroka's work is currently focused on improving vehicle robustness and reliability, as well as developing inexpensive marine sensors for classroom science and the next generation of AUV technology.

About the Brown Bag Lunch Series
MIT Sea Grant staff and students present projects, programs, research, and other topics in an informal setting to inform and inspire MIT colleagues and the wider community. The Brown Bag Lunch Series is open to the public.


The Odyssey IV is lowered gently into the ocean near Gloucester, MA, September 2010.

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