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NUPG April Meeting Report

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This month Alex Tasker gave us an insight into photogrammetry and his journey so far using this technique underwater.

Our usual focus at NUPG is capturing the beautiful scenes we see underwater in 2D, so turning these images into something in 3d so you can move around an object or underwater area on your laptop is a different concept and style of photography. Alex explained some of the history and theory of how this works and explained how he first got interested in this style of photography.

The historical side of things took us back to the thousands of images taken from spitfires in WW2 and the intelligence techniques that spotted the V2 rocket project. Alex’s own journey with photogrammetry first started with East Cheshire Sub Aqua Club’s Highball project and their aim to create a 3d model of one of the highball bombs in Loch Striven to allow non-divers to see what we are able to visit.

The theory started off making things sound relatively easy. The aim is to take lots of overlapping photographs of the subject from different angles. If there’s enough overlap each photograph has common points which the software can identify. The software can use both stills and video (by extracting individual frames from the video) and has the potential to use images from multiple sources to create the final 3d model, so the options on what camera to use are wide. After identifying the points in each image that match those in another image in the set and passing through multiple phases the software (hopefully) pops out a 3d model.

Alex’s first attempt was encouraging, on our ‘NUPG warm-up’ day in Capernwray last year he took hundreds of photos of Thunderbird 4 and produced a good 3d model (he obviously had 2 very patient buddies). Taking the photos that allowed this first attempt to work seemed easy, there was plenty of natural light and good visibility, the lesson learnt on this particular occasion was more about the patience required waiting for a laptop to process the images (or grind to a halt as the case may be). With the aim of the highball in mind though he needed to target objects in bad visibility, leading to trips to other well-known quarries where bad visibility and gloom are more readily found and an attempt to get a model of the hydrobox at Stoney Cove. The visibility on that occasion was so bad that the software thought some of the ‘muck’ in the water was actually part of an object and attempted to make it part of the model! This experiment also highlighted the challenges of getting images aligned, in bad visibility you need more overlap. The resulting model worked well for the top of the hydrobox but not the sides unfortunately. As with any form of photography though, practise is the key, so I’m sure another trip to the hydrobox will be on the cards this year.

At the beginning of March, Alex headed to Vobster Quay for a weekend to take part on the IANTD Photogrammetry course run by Tim Clements. He thoroughly enjoyed the course and got to pick up some tips from the likes of Simon Brown and Marcus Blatchford, who have a wealth of experience on this subject and have produced some amazing models (including entire wrecks and models that combine both underwater and drone photography). The course also got Alex thinking about the use of ‘angel lighting’. He’d been using his regular camera for the stills and attaching a video camera to the rig to collect additional data, having strobes and video lights on the same rig did add complications. By having his buddy carry the video lights it made using the video camera easier as a backup, gave his regular camera a better chance to focus and helped him easily know exactly where to find his buddy (not to mention giving his buddy something to do so she doesn’t get bored!)

Getting the images for photogrammetry is something any of us could do with our existing cameras. The challenges then become the amount of data generated from those images and the amount of processing power needed to turn them into a 3d model. There’s an amazing amount can be achieved by doing this though, from creating models of coral reefs to showing non-diving experts details of underwater wrecks. It will be interesting to see where his journey takes him over the coming months.

Winner by Justin Beevor

The monthly competition theme was Cephalopods. We had an array of fantastic images; the overall winner was Justin Beevor’s coconut octopus. Congratulations also go to Glynn Phillips whose octopus shot came in 2nd, and Maggie Russell who took 3rd place with a nicely isolated squid and also won the Compact category with her octopus entry.


The next NUPG meeting will be on Monday 13th May. This meeting will include talks by Roisin Maddison and Donovan Lewis on Videography and Sharks, as well as the NUPG AGM. The competition theme is “Action”.

For more information about the NUPG please visit their website by clicking here.

The Northern Underwater Photography Group (NUPG) is an organisation of like-minded people with an interest in taking images underwater. The group meets in Manchester but membership is drawn from around the North of England and further afield. Meetings are monthly and previous speakers have included Alex Mustard, Martin Edge, Alex Tattersall, and Scubaverse's own Nick & Caroline Robertson-Brown. Find out more at www.nupg.org.uk

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Historical Submarine Prototype protected

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The wreck of an early British submarine known as HMS/m D1, which was the forerunner to the Royal Navy’s patrol submarines that boosted Britain’s defensive power during the First World War, has been granted protection by the Department for Digital, Culture, Media and Sport on the advice of Historic England.

The wreck, off the coast of Dartmouth in Devon, was investigated in a project originated by U-boat historian Michael Lowrey, who was writing a book about First World War U boat losses. The wreck was identified by a team of technical divers who are skilled at diving at depths of over 40 metres, led by Steve Mortimer, diving from Wey Chieftain IV. They reported the discovery of HMS/m D1 to Historic England and it has now been protected by scheduling. This means divers can dive the wreck but its contents are protected by law and must remain in situ.

Multi-beam image of the newly- protected prototype of the D-Class submarine which was deliberately sunk off the coast of Dartmouth, Devon in 1918 and used as a target to test submarine detection equipment. Copyright Wessex Archaeology

HMS/m D1 was built by shipbuilding company Vickers at Barrow-in-Furness in Cumbria and was the secret prototype for the D-class, the Royal Navy’s first diesel powered submarine. Launched in 1908 and commissioned in September 1909, the D-class was a significant development on the C-class submarine, being larger and more powerful.

At the start of the First World War, HMS/m D1 was assigned to protecting the coast of Dover from enemy invasion before carrying out patrols outside of English territorial waters to monitor German shipping movements. In September 1917, HMS/m D1 joined the Portsmouth Local Defence Flotilla and a year later it was relegated to training duties. In October 1918, HMS/m D1 was decommissioned and scuttled- deliberately sunk. The submarine was used as a training target off the Devon coast for Royal Navy training exercises involving the detection of enemy submarines. The wreck sits upright and largely intact on the seabed.

Multi-beam image of the newly- protected prototype of the D-Class submarine. Copyright Wessex Archaeology

Duncan Wilson, Chief Executive of Historic England said: “The D-class submarine was superior to the C-class, with innovations that became integral parts of future Royal Navy submarines. These included diesel propulsion, twin propellers and a wireless telegraphy system which allowed the submarine to transmit and receive signals. This is a fascinating survival which deserves protection as an important part of our seafaring history.”

Lead Diver Steve Mortimer said: “Every diver dreams of identifying a historically important wreck.  Expecting to find the remains of a German U-boat, we were thrilled to discover a ground-breaking British submarine instead.  It’s tremendous that D1 is now protected but divers can still visit.”

Eight D-class submarines were built. HMS/m D2, HMS/m D3 and HMS/m D6 were sunk outside English territorial waters, while HMS/m D4, HMS/m D7 and HMS/m D8 were sold and scrapped in 1919. The wreck of HMS/m D5 is located off Lowestoft. Suffolk, and is protected under the Protection of Military Remains Act 1986.

For more information, please visit www.historicengland.org.uk

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Tried & Tested: INON UWL 95- C24 Wide Angle Wet Lens

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The INON UWL 95- C24 is the latest wide angle wet lens released by INON and has been designed for compact cameras with zoom lenses that are 24mm at the wide end. The UWL-95 C24 has a maximum angle of view of 95° underwater. This can be increased up to 141° with the optional Dome Lens.

The lens has a versatile M67 screw mount and M52 screw mount, the M52 fitting is already built in. Because the M67 rings are screwed to the lens over this, they can’t come loose like a step up rings. Totally renewed optical design effectively suppresses flare/ghost even in backlit condition to provide sharp and high quality image.

Test Conditions

  • Location: Capernwray Quarry, UK
  • Visibility: 2-3m
  • Temperature: 9 degrees C
  • No of Dives: 1
  • Equipment Used: Canon S110 in Recsea housing
  • Test Equipment: INON UWL 95- C24 with Dome Lens Unit 111A and 67mm thread.
  • RRP of lens and accessories used: £667.98

Review

This was an eagerly awaited new product from INON – a wide angle wet lens that can be used with hugely popular compact cameras such as the Olympus Tough and the Sony RX100 range. Testing new equipment in less than ideal conditions is always a challenge, but it is also a bonus, as for many, these will be the conditions they will experience too. Testing a new lens on an unfamiliar camera system also makes this process harder, as you need time to adjust to the new system, even though that is not what you are testing. My first impressions of this lens, before getting it underwater, was that it is very well made.

As we descended I started to unscrew the lens to ensure that any air trapped between camera housing and lens was released. As long as you do not undo all the way this works perfectly, however with thick gloves, in cold water, I would not want to have to attach the lens onto the camera using the 67mm thread very often as it feels a little fiddly.

Using the UWL-95 C24 can dramatically reduce minimum focusing distance needed between photographer and subject. As the visibility on the testing day was only 2-3m this was very good news indeed and the lens focused on subjects that were virtually touching the lens. Be careful not to get too close to anything that might scratch the lens! The lens, with the additional dome gave a really wide field of view, perfect for wreck, diver, scenic and large marine life shots.

Whilst the lens feels quite heavy on the front of a small camera out of the water, I did not notice it at all on the dive which is great, as some big lenses can require floats or very strong wrists to make them workable. This is a simple grab and go lens that does not need any additional kit or know-how to use. Alas, due to my buddy having a catastrophic dry suit flood, I only got a single dive to try it out, but was impressed with it nonetheless.

Fortunately I am taking the lens up to Scotland to try out on my Olympus TG5 whilst snorkeling and wild swimming – so watch out for more about this lens next month.

For more information visit the INON website by clicking here.

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Competitions

Explore the amazing triangle of Red Sea Reefs - The Brothers, Daedalus and Elphinstone on board the brand new liveaboard Big Blue.  With an option to add on a week at Roots Red Sea before or after. 

Strong currents and deep blue water are the catalysts that bring the pelagic species flocking to these reefs. The reefs themselves provide exquisite homes for a multitude of marine life.  The wafting soft corals are adorned with thousands of colourful fish. The gorgonian fans and hard corals provide magnificent back drops, all being patrolled by the reef’s predatory species.

£1475 per person based on double occupancy.  Soft all inclusive board basis, buffet meals with snacks, tea and coffee always available.  Add a week on at Roots Red Sea Resort before or after the liveaboard for just £725pp.  Flights and transfers are included.  See our brochure linked above for the full itinerary.

This trip will be hosted by The Scuba Place.  Come Dive with Us!

Call 020 3515 9955 or email john@thescubaplace.co.uk

www.thescubaplace.co.uk

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