Repeatable Robotic Surveying of Marine Benthic Habitats for Monitoring Long-term Change

This paper presents recent developments in data processing of multi-year repeat survey imagery and precision automatic registration for monitoring long-term changes in benthic marine habitats such as coral reefs and kelp forests. A method is presented for correcting underwater images for the effects of perspective-dependant lighting and attenuation in the water column. Additionally, two different methods are presented for precision alignment of imagery maps collected over multiple years. The first method employs scan-correlation optimisation using the topography generated via structurefrom-motion using the image data. The second method uses mutual information optimisation to register imagery maps, providing robustness to changes in the colour and brightness of objects in an underwater scene across multiple years. Results are presented from field data collected in Tasmania and Western Australia between 2009 and 2011.