TY - JOUR
T1 - Optimising protocols for high-definition imaging of historic shipwrecks using multibeam echosounder
AU - Westley, Kieran
AU - Plets, Ruth
AU - Quinn, Rory
AU - McGonigle, Chris
AU - Sacchetti, Fabio
AU - Dale, Mekayla
AU - McNeary, Rory
AU - Clements, Annika
PY - 2019/7/1
Y1 - 2019/7/1
N2 - Conservation of historic shipwrecks is prohibitively expensive and in situ preservation and recording are the preferred archaeological approaches. Non-destructive high-definition 3D imaging is therefore essential for recording and managing submerged historic shipwrecks. Multibeam echosounders (MBES), the standard tool for hydrographic survey, can produce point clouds to image complex 3D structures. However, wreck imaging is often done using MBES in traditional survey mode optimised for morphological characterisation of the seafloor. This does not necessarily provide high-definition imagery required by archaeologists. This study demonstrates key factors influencing high-definition MBES imaging of wrecks through a controlled field experiment. Results show that optimal high-definition 3D imaging is achieved through maximising the pulse rate, narrowing the angular sector, using the highest frequency and shortest pulse lengths, applied to at least 3 to 5 overlapping centreline-parallel and offset passes with additional perpendicular/oblique lines. Variations in survey design are demonstrated to exert strong controls on sounding density and distribution, with high-density on horizontal and vertical wreck surfaces enabled by a combination of overlapping passes and offset lines. Adoption of this method would result in more widespread high-definition 3D imaging of wrecks to benefit archaeological research and develop effective mitigation strategies to minimise loss of the fragile underwater resource.
AB - Conservation of historic shipwrecks is prohibitively expensive and in situ preservation and recording are the preferred archaeological approaches. Non-destructive high-definition 3D imaging is therefore essential for recording and managing submerged historic shipwrecks. Multibeam echosounders (MBES), the standard tool for hydrographic survey, can produce point clouds to image complex 3D structures. However, wreck imaging is often done using MBES in traditional survey mode optimised for morphological characterisation of the seafloor. This does not necessarily provide high-definition imagery required by archaeologists. This study demonstrates key factors influencing high-definition MBES imaging of wrecks through a controlled field experiment. Results show that optimal high-definition 3D imaging is achieved through maximising the pulse rate, narrowing the angular sector, using the highest frequency and shortest pulse lengths, applied to at least 3 to 5 overlapping centreline-parallel and offset passes with additional perpendicular/oblique lines. Variations in survey design are demonstrated to exert strong controls on sounding density and distribution, with high-density on horizontal and vertical wreck surfaces enabled by a combination of overlapping passes and offset lines. Adoption of this method would result in more widespread high-definition 3D imaging of wrecks to benefit archaeological research and develop effective mitigation strategies to minimise loss of the fragile underwater resource.
KW - Multibeam echosounder
KW - shipwreck
KW - marine geoarchaeology
KW - point cloud
KW - high-definition imaging
KW - best practice
UR - https://pure.ulster.ac.uk/en/publications/optimising-protocols-for-high-definition-imaging-of-historic-ship
U2 - 10.1007/s12520-019-00831-6
DO - 10.1007/s12520-019-00831-6
M3 - Article
SN - 1866-9557
VL - 11
SP - 3629
EP - 3645
JO - Archaeological and Anthropological Sciences
JF - Archaeological and Anthropological Sciences
IS - 7
ER -