A roundup of some of our favourite projects featuring photogrammetry in the UK (United Kingdom), both terrestrial and underwater and using a variety of capture techniques, tools and methods. There are a few development milestones worthy of mention as we review some of our favourite UK based projects over the last nine years.
Shipwreck – SS Gwladmena
This wreck lies in 38m of water at the entrance to Lerwick Harbour in the Shetland Isles. The ship was constructed in 1877 and originally called the Maggie Warrington by her first owner, before being sold in 1911. The ship was at anchor with a cargo of coal waiting for the fog to lift when the Danish vessel collided with her. All 16 crew were saved.
This wreck was scanned over two dives in August 2016 and took just over 2,000 images to capture the detail. This mini project proved firstly that data from two dives could be merged to produce a single robust model, and secondly swimming long distances at depth was tiring.
Physical effort at depth followed by decompression in cold water can induce a bend. Having suffered one Simon was keen to avoid another trip to the chamber, thus the use of a diver propulsion vehicle with camera mount was born.
The wreck was subject to sonar survey by Kevin Heath and the GPS data was extracted to provide scaling and location. This method should not be relied upon for accuracy, but in absence of anything better was considered acceptable and could be updated in the future if and when more accurate information becomes available.
Diver Propulsion Vehicles – UB116
The UB116 lies in Hoxa Sound, Orkney, and was the last U-Boat sunk during the First World War. The sub was also the first submerged vessel sunk on the 28th of October 1918 by a remotely controlled minefield. The full story of the submarine is covered in Simon’s iBook in far greater detail.
After swimming and scanning the Gwladmena Simon acquired an underwater scooter, fitted a camera and developed a more efficient way of capturing large subjects whilst reducing the risk of decompression sickness. The UB116 was not the first photogrammetry target in the UK to be scanned using a scooter but was the first proper shipwreck to be covered back in April 2017.
The ease of capture and reduced diver fatigue significantly improved our methods. We applied these skills to capture the much larger SS Thistlegorm later that year.
Close Range Photogrammetry – Pillboxes
During 1940 Britain was preparing to counter an invasion from across the English Channel, constructing hundreds of defensive bunkers at strategic points. All aimed to slow an enemy advance, but fortunately, no one tested them.
Many survive to this day and make excellent subjects for close range and handheld photogrammetry, or as targets for low-level drone flights.
Although the pillboxes are complex and challenging, they are small enough to cover in 200–300 images. Many remain open and accessible, so including the interior provides an added bonus.
Today, we repurpose some pillboxes for other uses. For example, authorities sealed the pair below to prevent public access. As a result, they now serve as homes for a bat colony.
This pillbox was dug into a Bronze Age burial mound for added protection. However, attitudes toward cultural heritage destruction have changed. Consequently, we have repurposed the pillbox as a base for a mobile phone mast.
Cultural Heritage – Sandsfoot Castle
Sandsfoot Castle sits on the cliffs overlooking Portland Harbour. Built by King Henry VIII in 1542 as protection against any invasion from France. The castle saw action during the English Civil War but by the early 18th century was a ruin.
Erosion has seen the gun emplacement fall into the sea and this site remains at risk from further collapse and the interior remains closed to the public. The site’s continued depredation makes it a prime candidate for photogrammetry in the UK.
This is a good example of how a short drone flight can capture and quickly record the current status of cultural heritage.
Geo-referencing lets us use the ortho mosaic to understand the original footprint of the building and identify what erosion has lost.
We manually rectified the original building plan in Global Mapper. Next, we overlaid it with the current data. Note that the gun battery platform (Marked C) is missing. Additionally, we found worked stone blocks scattered among the rubble on the beach below the cliffs.
Forensic Vehicle Collision documented with photogrammetry in the UK
AccuPixel will continues to hold the application of photogrammetry for forensic vehicle collision close to its heart. This contract was the company’s first win.
Undoubtedly, serious road collisions require investigation. Photogrammetry records evidence with a massive level of detail, and downstream analysis tools like PC Crash consume the outputs.
The use of drones and close range handheld images work well to capture the overall scene and all evidence of how the incident occurred.
Using a GoPro mounted on a camera pole, we captured the street scene above. Capturing key details in this way allows for fine detail analysis and provides a realistic scene and context to present to legal teams and a jury.
A drone captured this crossroad approach to enable a scan for a successful photogrammetry model in the UK. Real-world measurements set the level of accuracy and scale. This cost-effective method of scene reconstruction eliminates the need for real-time or post-processing corrective hardware and services.
Scan and Processing of these Cars by Bob Wagstaff using Zephyr (Photogrammetry in the UK).
Scaling allows you to take and record any arbitrary measurement for analysis purposes. You can also use dedicated software tools, such as PC Crash, to consume the digital assets themselves.
Drone Capture – Hastings Dinosaur Tracks for photogrammetry in the UK
The geology of the UK is a proper mashup of epochs and eras. Scotland contains the oldest rocks. The glacial deposits of gravel and flint along the River Thames valley represent some of the most recent events.
The south coast cliffs are a rich source of dinosaur fossils. It is a perfect environment for terrestrial photogrammetry in the UK. The sea and weather are eroding the cliffs that contain their bones. This constant erosion is continually exposing new finds. The beach at Pett Level near Hastings has bone deposits. However, preserved in the beach are the footprints and tail drag marks of a species of Iguanodon. This creature walked through a muddy lakebed some 180 million years ago.
Documenting this site took a high degree of patience. Waiting 3 years for the bedrock to be accessible through the process of storms eroding sand. The first attempt saw the loss of a drone. The second attempt saw the briefest of weather windows open for 3 hours timed perfectly with the lowest tides of the year.
The results were amazing and worth the wait. Local site expert Philip Hadland recorded new and previously unrecorded dinosaur tracks and summarized the results.
“The site at Fairlight Cove holds significant importance due to its exposure of layers from the Ashdown Beds, deposited approximately 140 million years ago, featuring dinosaur footprints and tail traces. These traces, mainly from Iguanodontids, provide valuable insights into dinosaur behaviors, including swimming, making it a unique resource for scientists studying dinosaur trace fossils. Given the constant erosion of the site by the sea, documenting it through 3D data is crucial for preserving this invaluable scientific record for current and future research.”
Close Range & Stereo Cameras for photogrammetry in the UK
Photogrammetry produces some wonderful models.Without scaling constraints or geolocation, their value becomes severely limited. Constraints add value by adding scale, allowing anyone to then seek answers to questions and to assist with artefact identification, collision tyre and tarmac gouge measurements, stockpile volume, or measuring stability/degradation of the subject.
Arranging and configuring cameras to work collectively sets the distance between sensors. As the constraint needed to scale the entire scene. In GPS denied areas, or subjects where adding scale bars is not advisable, then stereo cameras deliver accurate models.
Gathering positional data for constraints underwater are achievable with UWIS. However, measurement tasks by divers can be time consuming. The easiest way to derive scale is by using a pair of stereo cameras. But you can also add scale bars into a scene.
The purpose of two cameras working together is not to extend the survey area, but to derive scale. In the above example the differences between the real world and model measurements are <1%.
Finally, our Metashape Professional and 3DF Zephyr training courses discuss stereo cameras and their working datasets in greater detail.