I’ve been working on Reflectance Transformation Image capture in a sub-aquatic environment.  On 2 May, 2013 the first ever PTM file from an RTI dataset captured entirely underwater was successfully processed in the Archaeological Computing Research Group computer lab at the University of Southampton using RTIBuilder software.   Images were captured in 1.5 meters of water at the campus Jubilee pool using a common 12mpix digital camera and a 15 watt 1000 lumen HID dive-light.  The object photographed was a chunk of 18th century wooden ship ‘deadeye’ rig blocking found in the Itchen River in downtown Southampton.   The experiment was the first in a research design I’ve authored to assess the viability of  ‘Underwater RTI’…or what I’ve dubbed ‘URTI’.   Approximately 1540 photographs were taken over a 3-hour period in the pool.   The light radius was controlled by a piece of string spinning freely under the object via a heavy steal cylinder, and arc positions (4-6 per section, 13 sections) were entirely free-handed.   Seven independent sets of data were captured, and although only one of the sets produced acceptable results, the experiment proved the viability of RTI underwater.   Further research is forthcoming to continue the viability of RTI as an underwater diagnostic tool.  This summer I will be conducting baseline feasibility studies for the further development of technology and methodology in support of Reflectance Transformation Imaging in sub-aquatic environments. 

Dave Selmo notes camera settings and lighting configuration.
Raw image capture from ‘set 4 of 7’ used in the processed PTM file.


Camera mount improvised from dive shed rubbish and a 30″ Stilson pipe wrench.


JPG capture of the PTM file, diffused gain transformation applied.


Underwater Reflectance Transformation Imaging…a success.

David Selmo

Dave Selmo: mos11b1p@hotmail.com I’m a former US Army Infantry officer (of the Desert Storm generation), an avid open ocean technical overhead environment full-cave scuba diver as well as a PADI & BSAC open water dive instructor with a BA in English Creative Writing from Western Michigan University (Kalamazoo, MI. US). I discovered a passion for archaeology underwater through the Northwestern Michigan College (Traverse City, Michigan US) branch of Nautical Archaeology Society (NAS). It is there that I met visiting NAS tutor Mr. Ian Cundy of the Malvern Archaeological Diving Unit of Worcestershire, UK. He helped inspire in me that a high degree of professionalism (and fun!) can be achieved from non-vocational maritime archaeology. I’ve had the opportunity to utilize sector scan sonar imaging and then plan and execute a dive in Lake Michigan that resulted in the positive identification of a previously unknown shipwreck (the “B West”). That experience motivated me to further my studies in maritime archaeology. I completed formal training in sector scan sonar by one of the world’s leading experts in its development, Mr. Mark Atherton (Kongsberg Mesotech), and one of the world’s top independent operators of the equipment, Mr. Brian Abbott of Nautilus Marine Group (Pavlopetri). Ian, Mark, and Brian helped solidify my passion for archeology beneath the waves. In the summer of 2012 I served as PI for a NAS level 2 archaeological assessment survey of 19th century submerged remnants of a Michigan wooden shipping pier. (I co-drafted the proposal, secured permits, recruited volunteers, logistically provided for all aspects of the project, drafted press releases, gave television and radio interviews, and served as the lead diver on the project—a total station survey of 600+ submerged points in 5.5m of fresh water, up to 200+ m from shore.) It was a learning process that ultimately revealed to me a desire to take my maritime archaeology passion to the professional level. I’m interested in submerged paleolandscape, the submerged Florida Archaic period, Mesolithic in the Baltic, 16th-19th century shipwrecks, submerged Bronze Age in the Middle East, submerged cave archaeology, and the development of technologies and methodologies that support and enhance diver-lead maritime archaeology.

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