Rapid aerial photogrammetry with high-precision GNSS georeferencing enables experts to precisely monitor eruptions even under extreme conditions, helping to keep people safe.
Iceland is a hotbed of volcanic and seismic activity, so the country’s geoscientists need to be constantly aware of volcanic unrest and react quickly to new developments by mapping environmental changes and lava flows. This is one of the roles of the Icelandic Institute of Natural History (IINH), which runs a photogrammetry lab in collaboration with leading institutes in geohazards in Iceland. Since speed and safety are critical, the photogrammetry team prefer minimizing the number of people on the ground by using a small aeroplane over drones. Facing extreme conditions from volcanic plumes and adverse weather, their flight plans need to be flexible enough to work with what is possible in the air at each moment. Once the aircraft is safely back on the ground, the data then needs to be processed quickly and sent onwards for use by other agencies and actors, including by the Department of Civil Protection.
The eruptions near to Grindavík
There was a change in volcanic activity in December 2023, when a dramatic new fissure eruption began just north of the town of Grindavík, situated on the Reykjanes peninsula southwest of Reykjavík. This activity on the peninsula was preceded by three other eruptions in Fagradalsfjall, another volcano nearby, that started in 2021. Since then, the inhabitants of Grindavík have had to battle the forces of nature in ways no one wants to experience, including numerous earthquakes and eventually lava flows that reached the town. The task of mapping these lava flows is fulfilled by the photogrammetry lab of the IINH, directed by Birgir V. Óskarsson. “The area is very active now. We have had seven eruptions since 2021,” says Óskarsson. “We first had tectonic activity as precursors and then a series of eruptions as the ones above Grindavík.” During the volcanic unrest, the town subsided by more than one metre with the activation of faults, resulting in nearly 4,000 people being displaced and a lot of damage to houses and buildings from fire and subsidence. However, the people of Iceland are determined to fight against the forces of nature and are keen to protect their homes and businesses – but it is hard to predict when it will be safe for them to return.
The photogrammetry lab of the Icelandic Institute of Natural History:
• creates 3D models for photogeology
• conducts surveys of active environments such as volcanoes,landslides and glaciers
• monitors geoheritage sites
• monitors Surtsey island
• provides open access to data
Photogrammetry reveals trends and hidden dangers
High-resolution nadir imagery is essential in monitoring the hazards and allows the photogrammetry team to generate digital elevation models (DEMs), orthoimages and 3D mesh models, all to follow the progress and evolution of the lava field. By accurately mapping the flow and measuring the area and volume of the lava, the authorities can better mitigate the hazards and predict the course of the flows. They use a DEM to calculate the volumes erupted and estimate the lava effusion rate. By comparing two DEMs, the team can also gain insights into changes in the lava fields and can get a clearer idea of what is happening below the crust of the lava flows – which can inflate if the flow is obstructed, for example. “It is usually hard to see,” says Óskarsson. “But with these DEMs we can identify areas that are inflating and becoming dangerous. Because they can suddenly breakout, causing a sudden surge of lava, and if a lot of people are around that could mean fatalities.”
Specifying a new aerial system
As the photogrammetry lab of the IINH provides data used by the Civil Protection and others working with hazard assessment, its image collection and photogrammetric processing operations need to be extremely efficient. Previously, the IINH has used standalone cameras for volcano monitoring, and manually worked with the data. But without a proper aerial system,the processing was tedious. “It was crucial for us to acquire a full aerial system with the camera placed in a stabilizer, with a controller, flight management system, highprecision GNSS and inertial measurement unit (IMU): one proper system that plans the flight lines, with the correct number of images and overlap. That saves a lot of time on planning and processing the data,” Óskarsson explains. The IINH photogrammetry team uses aeroplanes with medium-format cameras because they can cover larger areas in a much shorter time than drones. Aeroplanes can also fly high, usually safely above the air traffic such as drones, helicopters and smaller planes. Moreover, drones need to be deployed from the ground, which is not always feasible in volcanic situations when drone operators would need to be located near dangerous hazards. “Our motto is ‘light and fast’; we have built our surveys around lightweight, medium-format cameras, meaning we can quickly install the system in the aircraft during an emergency and move towards the targeted area,” adds Óskarsson
Difficult conditions require flexibility to get results
When dealing with volcanic eruptions, flight plans with overlapping corridor patterns do not always stand up to the real-world challenges of volcanic plumes and associated turbulence. The surveyors often have to wait until it becomes possible to fly a line, and the plans often need to be improvised. When it is possible, the aim is to fly high in order to capture the area with the minimum number of images. But very often the Icelandic weather, with many cloudy and windy days, only allows for low flights at limited altitude. Consequently, taking oblique imagery is also part of the team’s toolkit. Having all images georeferenced with precise coordinates is a powerful advantage for Óskarsson and his team because it significantly reduces the need for people to be on the ground placing numerous physical control points around the lava flow. Ground control points are also frequently overrun by the lava and destroyed, requiring the team to replace them.
The Phase One solution
To meet the needs of the photogrammetry team, Phase One specified a PAS system. It comprises an iXM 100MP camera mounted in a small system frame,which is then mounted in a small SOMAG stabilizer. The camera is controlled by the iX MK5 controller with integrated Applanix GNSS and inertia l system. The Phase One software iX Flight Pro is also an essential element, resulting in an aerial system that is highly efficient and enables the team to cover an area in just a few minutes. “We chose Phase One because it is just on another level,” says Óskarsson. “Phase One is leading the market when it comes to aerial systems for medium-format cameras. We considered other suppliers, and some had most of the components, but none had all of them integrated nicely into one aerial system.”
He continues: “We are extremely excited about the results from our surveys so far. We have flown in all kinds of conditions – even around the solstice, when the angle of the sun is just two degrees in Iceland. Companies do not usually offer surveys when the sun is below ten degrees, due to the challenges of such conditions. It was quite cloudy too, but we still managed to get the data we needed.”
Easy planning saves time and adapts to changes
The flight planning software iX Plan has brought considerable benefits to the operations. “It is a game changer to be able to plan your flight to the extent the software helps you plan and then fly it. It is so much easier for everybody: for the pilot, and for us controlling the equipment to run the operation. It saves us a lot of stress and time,” Óskarsson says. The iX Plan software also helps them adapt their flight plans to the volatile reality in the skies around volcanoes. It enables the team to obtain the correct image overlap despite these conditions, considerably reducing their processing time later. “Because of the challenges with following the flight lines, I may need to do some improvisation, but the iX Flight Pro software allows for that. I can select a line that I want to fly by eyesight and then run the interval image capture. So I can do both: I can follow the lines and then improvise with other lines that I just make on the spot,” Óskarsson continues. Subsequently, the iX Process software helps him save time by giving an overview of the captured images that enables him to quickly select the images that he wants to process and piece together.
The Phase One solution enables the team to quickly deliver their results onwards to the many other agencies such as Civil Protection or companies planning rebuilding work who need to assess the dangers. The photogrammetry team sends data to Civil Protection within hours after a survey. The system helps to reduce processing time since it automates the image capture, and the stabilization compensates for the movements of the plane,ensuring images are all properly nadir and with good overlap.
Simplicity empowers more users
Making the surveying process easier has reduced the workload significantly. “In the past the flight lines were planned manually, but now we can plan them with iX Plan and even account for the fast topographic changes by integrating new DEMs from our surveys,” states Óskarsson. According to him, establishing a simplified process will also make it easier for other people to operate the system, such as when a long-lived eruption necessitates a larger team to rotate shifts. “It is very easy to plan low or high flights,” adds Óskarsson. “With Phase One’s system being user-friendly, we can train more people to run the operations.”
Ready for future projects
While the PAS system has become an essential tool for monitoring volcanic eruptions in Iceland, the photogrammetry team also plans to use it for landslide monitoring, glacial monitoring, glacial flood surveillance, monitoring the uninhabited volcanic island of Surtsey, and more. “There are many other places up on the highlands and in glaciers that are very difficult to access, where it is almost impossible for us to place control points. So having this system with high-precision GNSS georeferencing will save us a lot of headaches and work,” Óskarsson says. Subglacial volcanic activity can produce meltwater in vast quantities and cause dangerous floods. “We have had floods the size of the Amazon river, with 200,000m3 per second of flow when volcanoes erupt under glaciers,” says Óskarsson. “These cause a severe threat to the impact areas and therefore need to be monitored effectively, ” he states. Therefore, the photogrammetry team is now planning a project to investigate surface changes in glaciers caused by geothermal anomalies, as these could act as potential precursors of such eruptions. It is hoped that the resulting insights will contribute to advance warnings and emergency management measures to help keep people safe.