Underwater with a Sci-Fi Octopus: Learning Photogrammetry with Kotaro Yamafune

By Cherilyn Gilligan, Archaeologist

Editor’s note: This summer, we welcomed underwater photogrammetry expert Kotaro Yamafune (Kota, as he is referred to here) to lead courses on photogrammetry for our local diving community and join us as we put this technique to practice on some wrecks in Lake Champlain. Museum archaeologist Cherilyn Gilligan shares her experience and photos from a great summer with Kota below.

Photogrammetry is the practice of using photographs to create scaled and sometimes geo-referenced 3-D models, maps, and other imagery. This technology has many applications in the field of archaeology, and is especially useful to capture data from underwater sites where time to gather precise measurements and other data are limited by the environment.

The week-long intensive course with Kota was intense! We first explored the numerous outputs for producing models using photogrammetry – the documentation advantages, their usage for monitoring sensitive archaeological sites, and their effectiveness in the public sphere for the promotion of cultural heritage sites around the world. Then we dove into data capture and learning software. Kota has a great teaching method for introducing new software to new users that includes a watch-first-do-nothing approach and then requires the student to go back through steps and make mistakes. He would then meticulously explain how your mistake trickles down to your final model or affects the images that you are using. It was worth the agony because going through the motions with no written notes as guidance forces you to learn exactly what you’re manipulating and how. Then you can record notes that will allow you to follow the process more efficiently and avoid mistakes in the future. This was a difficult process for me – a ferocious note-taker. 

We created artifact models and site plans as practice projects, refreshing our camera manipulation skills, dealing with shadows and other lighting issues, and learning how to properly scale our models and geo-reference site plans. Kota has developed his methodology based on his experiences around the world – deep diving on sites with limited time to capture photographs – so his field methods are fast and efficient. With the skills we learned, we will be able to create 3-D site models of underwater wrecks and be able to extract valuable information – such as accurate measurements – right from the models we create. This has enormous potential for future research, making the study of our underwater sites far more accessible not only to us, as archaeologists, but to the public as well.  

Kota, his camera, and Chris Sabick, Archaeological Director

After the intensive course, Kota offered a 3-day course to avocational divers focused on data collection and model making. This course was geared towards easily accessible technology – using cameras that people already owned and finding cheaper software for processing models – and maintained a focus on the preservation value of photogrammetry in terms of documenting and monitoring sites. 

Kota and Chris in the water

After courses were over, Chris Sabick – the Archaeological Director at Lake Champlain Maritime Museum – and I had the opportunity to work with Kota in the field practicing our newly acquired skill sets in photogrammetry techniques at the Phoenix site, the Champlain II, and the Diamond Island Stone Boat. Watching Kota with his camera underwater is really a sight! He looked like a sci-fi octopus at a rave – four arms extend off of the camera housing holding strobe lights – they must stretch over 5 feet in full diameter – and Kota would quickly photograph an area in the proper search pattern, creating an eerie flickering glow over the surface of each wreck site. Silent machinery is fascinating. 

Fellow diver George with his camera underwater (Photo credit: Kotaro Yamafune)

Trouble shooting after dives back on the surface is where you get to learn minutia and the kind of on-the-fly finesse Kota brings to his work. Truly a photogrammetry master – it was a pleasure learning from him in a classroom setting and in the field. Can’t wait to have you back next year, Kota!