A new technology for mapping the seabed

There is an increasing need for improved mapping in the marine environment and industry for effective marine management. Traditional methods of seabed mapping and inspection are very time demanding as they are performed by reviewing countless hours of video, and results have a tendency to vary from person to person. How can this information be gathered and analyzed in a systematic, reliable way within reasonable man-hours?

A Norwegian company, Ecotone AS, delivers modern solutions for identification, monitoring and mapping of seabed features and marine installations.  Some years ago, the founders of Ecotone saw great potential in adapting remote sensing technology into underwater applications. Their prior knowledge with bio-optics and light in the arctic served as a springboard for testing new underwater sensors for improved mapping and detection techniques. Once the early prototype showed promise, Ecotone started to commercialize and patent the technology for Underwater Hyperspectral Imaging (UHI).

UHI provides an autonomous mapping tool that can provide detailed, accurate and unbiased map products from the seabed. With hyperspectral imaging technology, UHI reveals detail that have never before been achievable in the subsea sector. It is possible to not only identify objects but also to monitor their health and condition.

Typical UHI use cases include environmental mapping, pipeline inspection, mapping of drill cuttings, mineral mapping and subsea structure inspection. There are also other experimental use cases currently being developed, such as an in-situ detector of salmon lice.

Technology development and design in collaboration with Specim

UHI design has been done closely with Specim, exploiting Specim’s hyperspectral imaging technology.

“Specim was the preferred provider for several of our founder’s colleagues in the scientific community and, as such, was the first choice to develop the UHI. It was very important for us to work with a provider who could think outside the box and see our obstacles not as limitations but as challenges to overcome.

The main issue we overcame together was our requirement for a very light-sensitive imaging unit to counter the effects of the water. The imager was also required to be fitted into our underwater housing (without considerable work/dismantling). On several occasions, Specim stepped up, and we found a solution together,” says Jorgen Tegdan, Ecotone’s CTO.

How does Underwater Hyperspectral Imaging work?

UHI is an underwater push-broom scanner pointed towards the seabed and towed by a remotely operated underwater vehicle (ROV) along with a rig of external lights. Reflectance data are recorded in lines perpendicular to the ROV’s direction of movement as the light bounces back from the seabed and hits the scanner. Reflectance data are further processed to produce hyperspectral maps with location data. Using these hyperspectral maps, spectral libraries of different types of Objects of Interest can be produced. When used as an input to classification algorithms, large seabed areas can be automatically classified and Objects of Interest be identified.

Principle of UHI
Principle of UHI

The UHI works in concert with any other mapping tool, whether a straight line or a detailed mapping transect is required. Based on feedback from an initial transect, certain areas of interest can be revisited and examined in greater detail.

A 2D reconstruction of the seabed requires position and attitude data with accurate timing information
Positive ID of drifting algae attached to a manmade object at 600m depth. The object itself is covered with a mixture of biological growth and detritus, as well as a few living organisms (sponges)

Example: Salmon lice detection

Salmon lice is a parasite living on salmon. In salmon farms, where numbers of salmon live together in a net-cage, salmon lice population can grow so high that it causes severe threat both to farmed and wild salmon population. Counting salmon lice by traditional, invasive methods causes serious stress on the salmon. Also, small lice are often not detected. Having tools to automatically detect and count the number of salmon lice at any stage would offer the fish farming industry a possibility to take preventive actions against the damage caused by the lice.

Ecotone has invented a method that is able to detect salmon lice both in dead fish and on salmon swimming freely. They also found that lice of different stage have different spectral signature that can be identified with UHI. Further development is still required to be able to accurately tell the exact amount of lice in salmon swimming freely, but already now UHI can be used to detect trends in sea lice infestation. This method offers a notable opportunity to learn more about the trends of salmon lice population and infestation and plan preventive methods to protect the salmon population.

Example below shows four lice detected correctly.

Four lice detected on a dead salmon.

Endless number of applications

“Working with Ecotone has been a great chance for Specim to deepen our knowledge of both the requirements and possibilities in underwater hyperspectral imaging. Underwater deployment is again a fascinating example of the practically unlimited scientific and commercial potential of hyperspectral imaging. We are excited to have this opportunity and look forward to continued collaboration with Ecotone”, says Timo Hyvärinen, Founder at Specim.

Ecotone has taken great steps towards an automated mapping method to improve how we collect information about the seabed. They successfully use the spectral information in the seabed data to distinguish and characterize cold-water coral reefs and sponge habitats, as well as a range of its associated organisms such as lobsters, anemones and sea cucumbers. Ecotone has done this both as part of industry-standard visual surveys surrounding drill sites, but also in more experimental scenarios such as vertical walls covered with algae, corals and sponges.

Ecotone has also made great strides towards a method for mapping drill cuttings deposition following a drilling event. By using the spectral information from the top layer sediment, they can determine the extent of the deposition and yield information about the impact the drilling has had.

“We came to Specim with a somewhat unique challenge, and we feel that Specim has taken every step to provide the necessary work on the product they deliver to us, no matter how custom and challenging. In addition to delivering the imaging unit, Specim has been a valuable contact during the technology’s development phase. We feel that the team at Specim was excited about our ideas and gladly assisted us in our development.

We are exploring the ways to use hyperspectral data and what underwater objects are becoming visible to us that previously would have been very hard to detect using normal cameras. Based on our experiences, we are adapting and inventing new methods for image processing. We are still learning every day!” says Jorgen Tegdan.