Future Tracks – Photogrammetry and UWIS

Earlier this week saw three days of training delivered at Capernwray Dive Centre. The first two days were devoted to the IANTD underwater photogrammetry course with Agisoft Metashape processing the results. The third and final day covered topside preparation and underwater use of UWIS diver tracking and GPS data acquisition.

Classroom based photogrammetry training
Students busy in the classroom on the underwater photogrammetry course. Image courtesy Tim Clements

The principles are covered in the classroom and the lessons then applied underwater under the guidance of dive instructor Tim Clements. At the end of the course all students had mastered the concepts and processed their first models.

Divers gathering images for photogrammetry
Working as a team a pair of divers shoot images for 3D reconstruction. Image courtesy Tim Clements.

Tracking the Movement

The third day was devoted to the deployment and use of the UWIS hardware.

preparing UWIS for deployment
Preparing UWIS for deployment. Image courtesy Tim Clements

The first dive concentrated on tracking 4 divers concurrently as they navigated around the quarry. The instructions were simple – loop around some of the attractions and record their perimeter.

UWIS tracker software
The UWIS Tracker software screen showing the diver positions halfway through the dive.

The divers were gathering useful data just by swimming around and their tracks can be downloaded in several formats, including geoJSON for import into Blue Marble Global Mapper GIS software:

Global Mapper screenshot
Four diver tracks shown in Global Mapper with Ordnance Survey map layer

The loops record the position of two aircraft, a former minesweeper, a decommissioned diving bell and – incredibly small – a diver helmet.

By measuring the track we know the distance swam is just over a half kilometre (564m to be precise.) With depth being recorded Global Mapper’s Path Profile analysis reveals relative depth of the dive:

Global Mapper screenshot
Global Mapper with World Imagery satellite view layer, diver tracks and Path Profile analysis

With a wide range of supported import and export formats Global Mapper is a great editing, analysis and interpretation tool for clients working with geospatial data.

The 2D view has use but we do dive and record the track in a 3D world. We can visualise this by loading the UWIS log file into Global Mapper and using the really neat 3D viewing option:

3D view of the dive with surface data from satellite imagery. The track log visualisation in 3D opens up further analysis options

Working in 3D we can extract more information from the path – the actual track of the diver in context of where the other divers swam. In this clip we follow one diver into Capernwray and around one of the features. Adding in the photogrammetry model is the next step:

Here we follow a diver along the path taken during the dive. Adding in more content such as a photogrammetry model will give the scene more context, but for now we can visualise the tracks of other divers view

Jose has always rated Global Mapper and now Simon is converted…its ease of use and powerful tools are truly stunning.

Divers with UWIS tracker
Divers visible in the clear waters. The yellow UWIS diver units can be seen on the back of each diver

Diving with a Purpose

UWIS and the photogrammetry skills will be applied to a major project running in the North East. Benefitting from Heritage Lottery Funding the SeaScape project concentrates on the coastal and maritime heritage between two great rivers of the Tyne and the Tees.

The section of coast is littered with countless wrecks of all ages. Preserving this out-of-sight heritage in digital 3D is led by Newcastle University and will enable everyone – diver and non-diver alike – to fully appreciate these historical time capsules that lie in the deep.

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