In the 1980s archaeologists would spend weeks diving and drawing everything they saw by hand. Today a true picture of an underwater excavation can be created in a single dive with photogrammetry.
What is photogrammetry… something to do with photos?
Photogrammetry uses thousands of photographs taken as the diver swims slowly over the archaeological site with an underwater camera. The photos can be slowly stitched back together with computer software to create a 3D image. 3D images of individual objects can even be printed on a 3D printer, making exact copies that can be held in your hand.
Measuring from the comfort of your office
Archaeologists have found that the photogrammetry of the wreck site is so accurate that they can measure from the images to within a few millimetres accuracy. This reduces the amount of measuring you need to do on the seabed – a very difficult task when a strong current can seriously bend your measuring tape.
Bigger and more powerful
The 2017-2019 excavation of HMS Invincible was better funded than the first excavations in the 1980s thanks to fantastic funding bodies like the National Lottery Heritage Fund and LIBOR. The archaeologists were able to afford a bigger dive support boat and larger air compressors, which supplied bigger and more powerful dredging air lifts to suck the sand away. (A dredging air lift is the underwater version of the archaeologist’s trowel.)