8 minute read
TECHNICAL: Truk Lagoon Q&A
from Scuba Diver #52
We design, manufacture and retail scuba and rebreather equipment. We have fully equipped test and certification labs, and can pressure test large items in our vacuum chambers, as well as run fully automated leak test and dive simulations down to 400m. Our EMC and EMF lab is filled with state-ofthe-art equipment for testing electromagnetic compatibility and electromagnetic fields. We also have a large in-house laser for cutting and engraving on plastics and metals. www.narkedat90.com
Over the past three months, we have been showcasing the incredible photogrammetry from Truk Lagoon’s Project Baseline. Here we chat to Marcus Blatchford and Pete Mesley about the challenges of such an epic operation
Advertisement
COMPUTERS • O2 CELLS • GAS ANALYSERS CABLES & CONNECTORS • REBREATHER PARTS PATHFINDER STROBES • SENSORS view all products online TOOLS • SOLENOIDSwww.narkedat90.com
Q: What were your first thoughts when you became involved with the Truk Lagoon Project Baseline? A (MB): When Pete first put his idea to me, it was a complete surprise - the scale of the job is simply huge! I pointed out that there are two basic forms of 3D model, the first is a 3D representation that looks similar to the scanned object, the second is a scaled and potentially geo-referenced model of survey quality, the latter requiring a huge amount more work to be put in than the former. Pete’s initial project plan is more for more visual representation and comparison than being survey quality. Although survey quality would be great, the additional time, labour and equipment involved are simply out of our direct financial reach. Before committing I put a plan together of what I thought to be achievable on the first trip to try to ensure it was within Pete’s vision.
A (PM): This is going back quite a few years, I always remember thinking how cool it would be to be able to see the wreck in its entirety. Feeble attempts at photo collages about 15 years ago was the first attempts at this massive task. The results were average at best, then I kind of lost interest. Until recently. Over the last five or so years, photogrammetry has come into its own. I have wanted to create baseline models of these wrecks for so many reasons and just had to make a start. But I knew very little about it. This is where Marcus and I started getting into conversation about mapping these wrecks. Personally, at the time, my thoughts were ‘3D modelling isn’t really my thing. I am more of an ‘arty-farty’ photographer and modelling a wreck doesn’t really take any artistic skill, it’s just sit there and click away’.
But what I learnt the more I got into it was how honed in my observation skills got. I have dived these wrecks many, many times, yet when I started modelling these wrecks my understanding of the wrecks in their entirety increased a thousand-fold. The more I get into this, the more invested I am in learning more about these rusting hulks. There is a definite need for this sort of thing and my excitement grows every time I work on another wreck.
Deep inside an engine room Capturing the wreck images
Q: Shooting images to capture the data necessary for photogrammetry is a very different discipline to normal underwater photography. You are both very accomplished underwater photographers, how did you get to grips with this new style of photography? A (MB): Organic photography consists of two parts: 1) Creating an image that is exposed and focussed correctly; 2) Creating an image that is composed in a way to be appealing to the viewer. Once again, the latter is far more difficult to achieve than the former. Thankfully photogrammetry requires the images to be exposed well, in focus and have overlap with previous exposure – and, of course, a shed load of them! Composing the image is passed on from the photographer to the viewer. The viewer can rotate and zoom the model in the way they wish to see it.
A (PM): Being an ‘arty-farty’ photographer I really wasn’t looking forward to taking the thousands of images needed to capture the data needed to create these models. But it’s really quite challenging in its own right. We use techniques where the camera is mounted onto the scooter and we then set the camera up beforehand and off we go. So if you get the settings wrong, then all of the images won’t come out. So it has its own challenges. Once the camera is set up, then it becomes more of a ‘hoover’ the information up not missing any areas!
Q: Capturing thousands of images must be a daunting prospect at the best of times, but doing it at depth as in Truk Lagoon must have raised immense challenges in itself. A (MB): Thankfully I had been doing long, deep photogrammetry dives for a good few years previous to the project starting, over this time I have been able to buy the correct equipment for the job and make sure it all interacts together in the simplest of ways - this goes for not only the camera equipment but my life support equipment too. Pete’s equipment is very similar to mine - although I shoot Canon and he shoots Nikon - we both have JJ rebreathers which are pretty bombproof, we both use almost identical decompression gradient factors, our scooters (although different makes) have similar burn times and speeds - the biggest challenge is travelling with it all!
A (PM): It’s like most things, if you have complex tasks to complete, add depth to that equation, then you need to be on top of your game. I have spent many a dive getting absolutely nothing simply because I wasn’t properly prepared before the dive. So most of the bottom time would be eaten up getting the rig sorted out. I guess we learn the best through experience (learning the hard way!), so when there are tasks to do, and the wreck is in deep water, it’s really important to get things sorted before you get down. Or things just aren’t going to work out for the dive!
Q: If people have been intrigued by photogrammetry from the series of articles, how can get involved? A (MB): A number of training agencies are either in the process of or have released photogrammetry courses, I know that GUE and IANTD (UK only at the moment) already offer courses. I believe BSAC have a course, as do the Nautical Archaeology Society. There are also, of course, Facebook groups with many members who are more than happy to pass on their knowledge and experiences. The beauty of photogrammetry is that pretty much any camera can be used for scanning, so it truly is accessible to folks with action cameras right up to professional camera systems - even images from traditional film cameras can be used (although the cost of film and processing would probably far outweigh a the cost of a simple digital camera).
Pete with a ‘cheeky shiraz’ Truk’s wrecks are impressive
A (PM): My best advice. You need to do a course. You don’t need fancy gear, use what gear you already have. Start on small, digestible projects (don’t try and map a 500foot ocean liner for your first project). It’s best to take too much footage than too little. Understand that it’s not just gathering the image information, it’s also learning how to use the software. This all takes time. Be patient. Be persistent. And keep at it.
Q: What comes next for Truk Lagoon Project Baseline? A (MB): The Micronesian borders are still closed due to COVID. Their roadmap suggests that once they have completed their vaccine programme, they will start opening up again. When this happens, the project plans to continue.
A (PM): Why stop there right? Then I start thinking ‘How cool would it be if I mapped all the diveable wrecks in New Zealand?’ Then, I started talking to various people round the world who are doing their own thing with the 3D modelling. What if we could have a centre location site for everyone to be able to access these amazing models? A portal that people all round the world could share their work. The wrecks would be linked to their respective sites for information about them etc. All this, in turn, gave birth to the ‘World Wide Wreck Baseline Project’. This is a non-profit project so it will expand when more data comes available. There is a definite need for these models of wrecks for many reasons. The technology will only get better and the more people are partaking in documenting their local wrecks, before you know it we will have thousands of wrecks for all to enjoy in one place! n
