GeoConnexion | Bathymetry reaches new heights

SPH Engineering
January 13, 2021

GeoConnexion talks to Alexey Dobrovolskiy, CTO and co-founder of SPH Engineering, about the challenges and opportunities for drone-enabled bathymetry in shallow waters.

GeoConnexion (GEO): Bathymetry techniques and devices have traditionally been developed for use in deeper waters. How have you adapted these to accommodate accurate surveys of rivers, lakes, wetlands, lagoons, estuaries and other shallow waters?

Alexey Dobrovolskiy (AD): Although echo sounders are nothing new and have been used on unmanned surface vehicles and for “manned” surveys over many years, it was really by luck that we found lightweight survey-grade echo sounders suitable for deployment by a UAV on a suspended rope. These sensors have a minimal dead zone of around 15cm - allowing a practical minimum measured depth of around 30cm as they must be submerged when operating.

There are challenges, of course. Such sensors on the rope are not very stable when deployed and, to overcome this, we use additional stainless steel tubes to increase their weight and stability. Maintaining a set altitude over the water surface can also be problematic, but we had already solved this for other geophysical sensors (GPR, magnetometers, and metal detectors) that need to operate at fixed distances.

GEO: Do you foresee drone-enabled bathymetry replacing or supplementing traditional survey methods?

AD: We consider UAV-based bathymetry as a supplementing tool - or as the only choice when traditional methods don’t work.

If you already have an Unmanned Surface Vehicle (USV) with an echosounder, and can deploy and use it in a survey area, you don’t need a drone to do bathymetric surveys. However, it is important to use the right tool for the right task. A drone with an echo sounder is especially effective if one needs to make small-scale surveys in areas where the use of other tools is impossible or complicated.

We have found some real-world situations where the drone-deployed echo sounder can have great value. First of all - if you can’t deploy an USV for some practical reason, e.g. lack of physical access, then a drone-based solution allows you to do bathymetric surveys remotely. Another consideration is that the transportation, deployment and application of drones is a pretty simple process. A medium-sized drone with an echo sounder can be transported in any car and deployed by one person in minutes.

Last but not least. If you need or want to do bathymetric surveys but don’t have an USV, purchasing a drone with an echo sounder system will be at least half the cost of an USV with an autopilot and echosounder of the same quality and precision. If you already have an appropriate drone, you will save at least two thirds of the cost.

GEO: Fully autonomous drones are said to be the “next big thing” in maritime surveying. Does your work on Artificial Intelligence and Machine Learning bring this closer?

AD: Yes. Our ATLAS data analytics system is based on AI and Machine Learning. We are also developing GPR data analysis using AI. We already have some good examples of how ATLAS can be used to analyse the data gathered using side-scan sonars

GEO: The United States is currently your largest market outside Europe. Do you see this changing in the medium-to-long term?

AD: The current situation is that the USA is a huge market in itself and businesses there are quick to adopt new technologies. There are no significant language and cultural barriers. For these reasons, I think that the USA (+Canada) and the EU will continue to be our biggest markets. That said, we are working hard to sell more to other regions.

GEO: BVLOS flying has traditionally limited the operating range for Unmanned Aerial Systems. Will the new European regulations due to come into effect at the end of 2020 ease this limitation for offshore surveys?

AD: We still don’t understand how things will work in practice, so it’s a case of wait and see. At the moment, we have experience of cross-border (between Latvia and Estonia) BLOS flights, and getting permissions was not an easy task.

GEO: SPH Engineering entered into a partnership to integrate its UgCS software solution for bathymetry with Eye4Software’s Hydromagic Survey software. How do you see this advancing the process of bathymetric and hydrological data collection using drones?

AD: When integrating new sensors and software, we aim to offer customers end-to-end solutions - from data collection tools up to software for data processing and reporting. This doesn’t mean that we build everything ourselves; rather we explore new products on the marker that can complete the whole picture. For bathymetry, we found Hydromagic an excellent tool for data processing and reporting.

Together with the Eye4Software team, we guaranteed compatibility of data files generated by onboard drone software with Hydromagic. NMEA 0183 with bathymetric data, and SEG-Y files with full echo sounder data, can all be processed with Hydromagic to produce output results (depth maps, cross-sections, contour maps, 3D models) according to end user requirements.

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