Underwater reflectance transformation imaging: a technology for in situ underwater cultural heritage object-level recording

TY - JOUR

T1 - Underwater reflectance transformation imaging

T2 - a technology for in situ underwater cultural heritage object-level recording

AU - Selmo, David

AU - Sturt, Fraser

AU - Miles, James

AU - Basford, Philip

AU - Malzbender, Tom

AU - Martinez, Kirk

AU - Thompson, Charlie

AU - Earl, Graeme

AU - Bevan, George

N1 - Related to the paper: Archaeological applications of polynomial texture mapping: analysis, conservation and representation M1 - 011029

PY - 2017/2

Y1 - 2017/2

N2 - There is an increasing demand for high-resolution recording of in situ underwater cultural heritage. Reflectance transformation imaging (RTI) has a proven track record in terrestrial contexts for acquiring high-resolution diagnostic data at small scales. The research presented here documents the first adaptation of RTI protocols to the subaquatic environment, with a scuba-deployable method designed around affordable off-the-shelf technologies. Underwater RTI (URTI) was used to capture detail from historic shipwrecks in both the Solent and the western Mediterranean. Results show that URTI can capture submillimeter levels of qualitative diagnostic detail from in situ archaeological material. In addition, this paper presents the results of experiments to explore the impact of turbidity on URTI. For this purpose, a prototype fixed-lighting semisubmersible RTI photography dome was constructed to allow collection of data under controlled conditions. The signal-to-noise data generated reveals that the RGB channels of underwater digital images captured in progressive turbidity degraded faster than URTI object geometry calculated from them. URTI is shown to be capable of providing analytically useful object-level detail in conditions that would render ordinary underwater photography of limited use.

AB - There is an increasing demand for high-resolution recording of in situ underwater cultural heritage. Reflectance transformation imaging (RTI) has a proven track record in terrestrial contexts for acquiring high-resolution diagnostic data at small scales. The research presented here documents the first adaptation of RTI protocols to the subaquatic environment, with a scuba-deployable method designed around affordable off-the-shelf technologies. Underwater RTI (URTI) was used to capture detail from historic shipwrecks in both the Solent and the western Mediterranean. Results show that URTI can capture submillimeter levels of qualitative diagnostic detail from in situ archaeological material. In addition, this paper presents the results of experiments to explore the impact of turbidity on URTI. For this purpose, a prototype fixed-lighting semisubmersible RTI photography dome was constructed to allow collection of data under controlled conditions. The signal-to-noise data generated reveals that the RGB channels of underwater digital images captured in progressive turbidity degraded faster than URTI object geometry calculated from them. URTI is shown to be capable of providing analytically useful object-level detail in conditions that would render ordinary underwater photography of limited use.

KW - imaging

KW - RTI

KW - Archaeology

KW - underwater

KW - cultural heritage

KW - turbidity

KW - polynomial texture mapping

KW - maritime archaeology

U2 - 10.1117/1.JEI.26.1.011029

DO - 10.1117/1.JEI.26.1.011029

M3 - Article

SN - 1017-9909

VL - 26

JO - JOURNAL OF ELECTRONIC IMAGING

JF - JOURNAL OF ELECTRONIC IMAGING

IS - 1

M1 - 011029

ER -