Photogrammetry transforms an afternoon snorkel into impactful data
Tropical reefs are labyrinthine structures of sprawling corals, branching sponges, and carpet-like anemones. Thanks to cutting-edge photogrammetric software powered by cloud-computing, we can now accurately map this complex mosaic without disturbing its inhabitants. With training from scientists at Citizens of the Sea, sailors can map the seafloor in three dimensions, turning photos from their snorkeling trips into valuable scientific data.
From 2D snapshots to 3D models
Photogrammetry is an ingenious technique for inferring detailed, three-dimensional structures from the distortion observed through a wide-angle camera lens in a series of overlapping images. Powerful, the cloud-based photogrammetric app Polycam reconstructs the intricate shape of a reef from photos snapped every second or two by snorkelers swimming above a seabed. The software can map 100 square meters of reef in one pass.
Scale and geographical positioning leap from guesswork to precision with the inclusion of a north-facing scale marker placed on the reef and the integration of GPS data from surface shots. The addition of a color card in the frame allows scientists to infer the health of the coral. Best of all, volunteers can explore their own, interactive 3D models via web browser or mobile app within minutes of capturing the data, promising a fun and rewarding experience.
By encouraging future citizen scientists to revisit previously photographed sites, Citizens of the Sea will generate long term data on reef health. Data will be available for anyone to view, and downloadable by scientists collaborating with Citizens of the Sea.
The citizen scientists making waves
Citizen science democratizes scientific research and discovery. This inclusive approach to photogrammetry means that anyone with a waterproof camera—be it a GoPro, smartphone, or specialized diving equipment—can map a reef. But some of the reefs most in need of conservation and scientific exploration are on remote South Pacific islands few tourists will ever reach–with the exception of sailors.
That’s why Citizens of the Sea has recruited a fleet of 25 sailboats navigating waters from New Zealand to New Caledonia via Tonga and Fiji as part of a rally held by the Island Cruising Association. Crew from each vessel will be trained in person to obtain quality images for photogrammetric analysis. Working closely with local scientists, conservation groups, and communities, sailors will build strong connections between Citizens of the Seas and local communities.
See, Care, Act
Using virtual reality tools, members of the public who have never dipped a toe in the ocean will soon be able to immerse themselves in the mesmerizing patterns of a brain coral or contemplate the spines of a sea urchin in one of Citizens of the Sea’s three-dimensional models.
Being able to visualize reef structures and health is as important for policy makers as it is for local communities. Awareness is a crucial first step towards conservation. Photogrammetry empowers us to document, share, and ultimately protect our oceans by bringing their hidden marvels into the light.
