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For too long, discussions about hydrographic surveying methods have centered on comparing and contrasting individual technologies – multibeam vs. lidar, lidar vs. satellite, satellite vs multibeam. This “either/or” and one vs the other mentality is outdated. Each of these methods, whether using sound, light, or reflectance, is an imperfect tool for measuring a complex environment. Instead of debating the merits of one approach over another, we need to embrace a “both/and” strategy. The future of hydrography lies in intelligent integration, seamlessly combining diverse technologies for maximum efficiency, cost-effectiveness, and environmental responsibility. This article argues for a paradigm shift: moving from sequential, siloed approaches to a holistic, vertically integrated model that leverages the unique strengths of each technology.

Read on Hydro International

The Inefficiency of the Status Quo:

Current practices often fall short. We see examples of operational inefficiencies: lidar flights over remote islands without prior weather or water condition checks via readily available or tasked satellite imagery; repeated topobathy lidar reflights for small areas easily filled by satellite data; small vessel surveys in coastal zones running aground on unsurveyed shoals – all preventable with integrated approaches. Even in regions with open data policies, the time lag between data collection and availability can be significant, especially given the rate of environmental change. These operational gaps are not just inconvenient; they often represent wasted taxpayer dollars and missed opportunities for enhanced safety. A cost-focused argument demands that we maximize the value of every survey, prioritizing operational efficiency and focusing on desired outcomes, not simply sensor-based specifications.

A Vision for Integration:

Imagine a hydrographic workflow where satellite-derived bathymetry (SDB) informs and improves topobathymetric lidar acquisition, identifying optimal flight times based on daily water clarity trends, minimizing reflights. SDB then serves as a planning tool for multibeam surveys, optimizing track lines and enhancing safety by highlighting potential hazards. This integrated approach is not just theoretical. We see promising examples like Land Information New Zealand’s (LINZ) forward-thinking approach in New Zealand, mandating water condition tracking to optimize bathymetric lidar collection. 

The hydrographic landscape is transforming, and integrated hydrography is no longer just a vision; it’s a necessity.

Kyle Goodrich; TCarta President & Founder

SDB and other Earth Observation (EO) data also have use as the geospatial “glue” connecting land and sea, bridging the intertidal zone and providing a valuable baseline for higher-resolution data. A recent example of this approach can be seen on NOAA’s Office for Coastal Management (OCM) with an example of high resolution topobathymetric models with SDB included at the coastline, bridging the gap between hydrographic data and topography in a challenging location for coastal mapping: Alaska.  

This integration extends into unmanned vessel data acquisition. SDB can de-risk USV operations through mission planning and hazard avoidance. The technology exists today for satellite-derived electronic charts to provide reconnaissance for a USV operating in remote islands in the Pacific Ocean with digital chart information delivered via space-based high speed internet.

Reversing the situation, information from lidar collection and in situ measurements from field operations can inform and improve SDB models, creating a powerful feedback loop for continuous improvement. USVs can provide valuable in situ for validation of SDB surfaces where other means are not available. This is technology integration: a full stack of sensors, from satellites in space to underwater vehicles and seafloor devices, focused on a challenging problem: mapping and characterizing the ocean floor and coastal zone.

Overcoming Barriers and Embracing the Future:

Several barriers or disincentives hinder widespread integration. Government RFQs and framework contracts often contract out individual survey technologies separately, discouraging integrated solutions. The biggest obstacle may be mindset. We must move beyond the “either/or” thinking and recognize the synergistic potential of integrated approaches. This requires a shift in RFPs and framework processes, requiring integrated solutions and focusing on the best approach for the specific location, not just a pre-determined platform or survey method.

The rise of the blue economy, with its increasing emphasis on environmental monitoring, further strengthens the case for EO in coastal mapping. With advancements like wave kinematic bathymetry, space-based lidar’s well-proven capabilities, and the development of high-resolution customizable hyperspectral satellites, the future of satellite-based hydrography itself is multi-modal and one of integrated techniques.  Perhaps that is what draws ‘future hydrographers’ and next generation ocean explorers to the alternative hydrographic method of satellite based surveying.

Parting Thoughts:

The hydrographic landscape is transforming, and integrated hydrography is no longer just a vision; it’s a necessity. By combining the strengths of diverse technologies – from SDB and lidar to multibeam and USVs – we can unlock unprecedented levels of efficiency, cost-effectiveness, and environmental stewardship. This integrated approach isn’t just about better data; it’s about a deeper understanding of our oceans and a commitment to a sustainable future. Recent industry developments, such as the acquisition of a leading satellite-derived bathymetry and Earth observation company by the world’s largest hydrographic survey firm, signal a clear trend: the future of hydrography is vertically integrated. Earth observation is no longer a niche technology but a core component of modern hydrographic solutions. This acquisition validates the growing importance of SDB and EO and underscores the value of integrated services for an “all-sensor” approach. To further accelerate this evolution, my company encourages collaboration and partnerships in this arena. It’s time to move beyond “either/or” and embrace the power of “all of the above and below,” working together to shape the future of hydrography.

Shallow coastal zones are where most ship groundings occur, and they are also where the most inaccurate and outdated information on official nautical charts resides. TCarta, a provider of hydrospatial mapping services, has introduced a new line of Satellite Reconnaissance Charts to supplement official marine navigation maps in shallow waters.

Read in LiDAR Magazine

TCarta will introduce the new Satellite Reconnaissance Chart products to the hydrographic community on Tuesday, February 25, at the 2025 Esri Federal GIS Conference in Washington, D.C.

Derived from recently acquired satellite imagery, TCarta Satellite Reconnaissance Charts are digital maps adhering to International Hydrographic Organization S-57 and S-100 data model standards with the same appearance and symbology as official navigation aids. However, the TCarta Charts do not replace official nautical map products, which are primarily designed for marine navigation in commercial shipping lanes.

The new TCarta Satellite Reconnaissance Charts contain up-to-date details of seafloor depths, sandbars, reefs, shoals, and other submerged hazards – along with floating dangers – in the near-shore environments that are often poorly mapped or out of date on official maritime charts. Offered at off-the-shelf 1:20,000 scale and custom 1:4,000 scale, the TCarta products are delivered in file formats ready to load into popular marine navigation software as well as common GIS software platforms.

“We launched the Satellite Reconnaissance Charts to enhance the awareness and safety of vessels operating in shallow waters, such as recreational boats, private yachts, fishing vessels, and military ships,” said TCarta President Kyle Goodrich.

Another major user of these products, however, will be government hydrographic offices, explained Goodrich. The TCarta Charts will serve as accurate and timely guides for those organizations to plan hydrographic surveys to update official nautical charts, especially in dynamic coastal zones, enabling their operations to be more efficient and avoid hazardous situations.

“Collection of high-quality water depth measurements in shallow coastal areas is expensive and dangerous to acquire by ship or aircraft, notably in remote or contested regions,” Goodrich said. “Our Satellite Reconnaissance Charts will help reduce risk, time and costs in coastal hydrographic surveying.”

The Satellite Derived Bathymetry (SDB) technology refined by TCarta and used to create the new Reconnaissance Charts is uniquely suited to measure water depth accurately and inexpensively while posing no danger to personnel, equipment, or coastal ecosystems. SDB applies physics-based computer algorithms to optical imagery captured by commercial remote sensing satellites. This analysis detects and measures light reflecting off the seafloor to calculate water depth. Depending on water clarity, SDB is accurate to depths of 20 to 30 meters.

TCarta has mapped nearly one third of the world’s coastlines with SDB and offers products in custom and off-the-shelf versions. Custom SDB data sets are typically generated using high-resolution satellite imagery capable of resolving seafloor objects, such as shoals and reefs, with one-meter resolution. Satellite Reconnaissance Charts can be created for nearly any shallow-water area in the world and are available off the shelf now in the following regions:

• Caribbean
• Arabian/Persian Gulf
• Red Sea
• Many Pacific Islands
• Florida and Mexican Coasts

Satellite Reconnaissance Charts are available for specific locations, regions, and entire countries.  Commercial organizations may order bathymetry products directly from TCarta and the US government can purchase through the GSA Schedule.

Multiple recent incidents in which naval and commercial vessels ran aground have highlighted the dangers of maritime operations in shallow or poorly charted coastal waters. TCarta Marine of Denver offers a cost-effective, environmentally safe solution using Earth observation satellites to derive accurate water depth measurements in near-shore areas.

Read in Environment Coastal & Offshore Magazine

“While the exact causes of recent ship groundings off the coasts of Oman, Greenland, and Fiji are under investigation and often complex, the risk of such accidents can be significantly reduced with up-to-date bathymetric data produced from satellite imagery,” said TCarta President Kyle Goodrich. “Often in coastal areas, the regions outside commercial shipping lanes are poorly charted or not surveyed.”

Unfortunately, the collection of high-quality water depth measurements in shallow coastal areas – where they are needed the most – has traditionally been expensive and dangerous to acquire with ships or aircraft, especially in remote or contested regions, Goodrich said. And the risk of groundings is only growing as military vessels and eco-tourism charters increasingly operate in unfamiliar and inadequately mapped coastal zones.

For over 10 years, TCarta has been supplying marine charting organizations with water depth data using a technique called Satellite Derived Bathymetry (SDB). SDB applies physics-based computer algorithms to optical imagery captured by commercial remote sensing satellites. This analysis detects and measures light reflecting off the seafloor to calculate water depth. Depending on water clarity, SDB is routinely accurate to depths of 20 to 30 meters.

“In addition to posing no danger to personnel, equipment, or coastal environments, satellites are more cost effective than ship-borne sonar or airborne laser scanning because they acquire image data over large regions in seconds,” said Goodrich. “And because satellites orbit without geographic restrictions, data can be collected for areas otherwise off limits to vessels or aircraft.”

TCarta has mapped nearly one third of the world’s coastlines with SDB and offers products in custom and off-the-shelf versions. Custom SDB data sets are typically generated using high-resolution satellite imagery capable of resolving seafloor objects, such as shoals and reefs, with one-meter resolution.

The off-the-shelf bathymetry product Global Satellite Derived Bathymetry (G-SDB) offers 10-meter detail and is ideal for identifying coastal shoals in remote areas that don’t appear on nautical charts. Large-area contiguous G-SDB products are immediately available for more than a dozen critical locations, including:

• South China Sea
• Arabian/Persian Gulf
• Gulf of Oman
• Red Sea
• Black Sea
• Eastern Mediterranean

Government and commercial organizations may order bathymetry products directly from TCarta or through the GSA Schedule.

Five members of the Dominican Republic Navy received training and instruction to work on detecting sargassum

Read in elCaribe

Members of the Dominican Navy received training to work on sargassum detection and Satellite Derived Bathymetry (SDB). In addition, participants received additional training on how to identify sargassum using satellite imagery. However, sargassum is known to come to our beaches and coastal areas, creating a nuisance for both tourists and locals. Likewise, this multi-day training was made possible thanks to the collaboration between the Nippon Foundation-GEBCOSeabed2030 project and TCartaMarine with the Dominican Navy.

This training comes at a very important time considering that the country’s Hydrographic Service has been inactive for around 30 years. Since 2015, great efforts have been made to learn new technologies and experts within the Navy and contribute to the country.

Nippon Foundation and its help in the detection of sargassum

A collaboration between the Nippon Foundation and the General Bathymetric Chart of the Ocean (GEBCO), which operates under the joint auspices of the International Hydrographic Organization and the Intergovernmental Oceanographic Commission (IOC) of UNESCO, Seabed 2030 is a global accelerator of ocean mapping. Seabed 2030 inspires the complete mapping of the global ocean by 2030.

The Dominican Republic has been a member of the IHO since 1967. Just last year at the National Palace, President Abinader received the Director of the IHO, Luigi Sinapi. There, the sustainable use of the oceans and the importance of hydrography in the Dominican Republic were discussed. SDB is an ideal method for collecting bathymetry measurements in shallow waters. TCarta founder Kyle Goodrich on the importance of training for communities and institutions around the world.

Advances in hydrography in the Dominican Republic

Thanks to the Commander General of the Navy, Vice Admiral Agustín Morillo Rodríguez , members of the Navy received training in how to process and compile SDB data. Including Frigate Captain Primitivo López, Director of the Hydrographic Service

Sheila Caceres, a member of the Seabed 2030 Atlantic and Indian Ocean Regional Centre. She helped establish this collaboration and training opportunity, and is attending the training event.

In addition, this training is a set of national coastal bathymetry data with ten-meter resolution generated by the Hydrographic Service. This for use in environmental models, conservation efforts and other specialized uses within the Service. In addition, this training leaves a group of technical experts in SDB for the Navy. With the capacity to continue developing, transmitting the knowledge and skills learned. The objective is to update nautical charts in order to have safe navigation for ships in jurisdictional waters.

Read in The American Surveyor

TCarta Marine, a global provider of hydrospatial products and services, has delivered three major satellite derived bathymetry (SDB) data sets to The Nippon Foundation-GEBCO Seabed 2030 project. Students in Canada participating in a 2023 summer internship program created the SDB products for the entire coastline of Madagascar, Newfoundland, and two Canadian Arctic research areas.

TCarta co-sponsored the first-of-its-kind SDB Internship in cooperation with Seabed 2030 and the Marine Institute (MI) of Memorial University in Newfoundland, Canada. Held at the MI Ocean Mapping facility in St. John’s, the program instructed six undergraduate and two graduate hydrography students in the use of SDB processes, satellite Earth observation platforms, advanced sensor systems, and artificial intelligence for seafloor mapping.

“As is true of most Seabed 2030 data sets, these bathymetry products will be applied in local projects as well as the global program,” said Kyle Goodrich, TCarta President. “The Canadian Arctic data, for example, will be used in fisheries research conducted by the Marine Institute.”

Goodrich will present details of the summer 2023 project at the Map the Gap Symposium being held Nov. 7-8 in Monaco.

Launched by The Nippon Foundation of Japan and the General Bathymetric Chart of the Oceans (GEBCO) program, Seabed 2030 seeks to inspire the complete mapping of the entire ocean floor by the end of the decade. A flagship program of the UN Ocean Decade, the data will be publicly available and will support coastal resilience, environmental protection, and other marine applications.

“This collaborative internship co-sponsored with our partners Memorial University and TCarta has enabled students to acquire cutting edge hydrospatial skill sets,” commented Seabed 2030 Project Director Jamie McMichael-Phillips. “The SDB data sets provided by students of the summer internship will be instrumental in supporting the global effort underway to deliver a complete map of the ocean floor by 2030.”

The student internship program is one facet of TCarta’s international capacity building initiative that seeks to instruct hydrographers worldwide in the production of SDB data for their coastlines. Training focuses on the use of TCarta’s Trident SDB Toolbox, a series of software applications running within Esri ArcGIS Pro to extract water depth measurements from remotely sensed imagery with Machine Learning and satellite LiDAR.

Processing government and commercial multispectral satellite imagery, the 2023 summer interns generated 10-meter resolution SDB data to depths of 25 meters along the Madagascar coast and 20 meters in Newfoundland, and seven to eight meters in the Canadian Arctic locations. NASA ICESat-2 LiDAR data was used for validation, a new technique developed by TCarta.

Coastal Madagascar was a challenge due to its geographic size and shallow water turbidity, while the murky Arctic waters were difficult due to several factors, including the scarcity of ice-free satellite images. In recent years, TCarta has significantly enhanced the utility of SDB technology in turbid, murky water conditions leveraging grants from the National Science Foundation (NSF) and National Oceanic & Atmospheric Administration (NOAA).

The two Canadian Arctic SDB data sets will also be used in Memorial University marine research activities.

“SDB is a natural fit with the in-situ soundings collected through the Qikiqtaaluk Fisheries Corporation’s Community Hydrography project and delivered through TCarta and the Marine Institute, focused on the community’s priorities and local knowledge of on-water access to their traditional hunting and fishing areas in the Qikiqtani region of Nunavut,” said Kirk Regular, Marine Geomatics Researcher at the Centre for Applied Ocean Technology at Memorial University.

TCarta Marine, a global provider of hydrospatial products and services, has been awarded a contract to deliver satellite derived bathymetry (SDB) and seafloor classification data for the coastal zones of 13 regions around the world to the National Geospatial-Intelligence Agency (NGA) under contract to Maxar Technologies.

TCarta will deliver seabed depth and feature maps from high-resolution multispectral Maxar WorldView-2 and WorldView-3 satellite imagery for the 13 regions. SDB measurements are accurate to depths of 20-30 meters depending on water conditions, with two-meter spatial resolution. Feature classification includes coral reefs, large rocks, sandbars, and other navigation hazards.

TCarta has processed thousands of Maxar satellite images for the project, including hundreds of high-resolution scenes for one nation alone. By the time all deliverables have been submitted and approved by NGA, TCarta will have mapped the entire subsurface coastlines of the 13 regions over the 12-month Period of Performance.

“This is the most ambitious SDB mapping program ever conducted in terms of both geographic area and timeline,” said TCarta President Kyle Goodrich. “In particular, one 7,239-square-kilometer coastline by itself is larger than any contiguous SDB project TCarta has undertaken.”

“SDB can be particularly useful for remote or hard-to-access locations and for areas where traditional survey methods are too expensive or time consuming,” said Jennifer Krischer, Maxar’s Vice President and General Manager, Intelligence Programs. “The partnership between Maxar and TCarta offers a valuable service to NGA for accurate and efficient bathymetric data collection, which reflects NGA’s renewed emphasis on collecting data and generating insight ‘from Seabed to Space’.”

A leader in the application of SDB technology worldwide for more than a decade, TCarta has played a key role in enhancing the traditional water depth extraction methodology. With funding from Small Business Innovation Research (SBIR) programs managed by NOAA and the National Science Foundation, the Denver firm has integrated machine learning algorithms into the processing workflow and introduced the use of space-based laser data from the NASA ICESat-2 satellite to validate SDB results.

“A major challenge with this project was the variety of turbid and silty water conditions encountered in different geographic regions, but NGA has been receptive about the results,” said Goodrich. “We have bolstered and refined our existing workflows to deliver products that meet NGA requirements.”

View this article here: https://www.prnewswire.com/news-releases/tcarta-to-deliver-satellite-derived-bathymetry-for-13-regions-to-national-geospatial-intelligence-agency-301848893.html#:~:text=DENVER%2C%20June%2013%2C%202023%20%2F,the%20National%20Geospatial%2DIntelligence%20Agency%20(

Baffin Island Project Announced

TCarta Marine, a global provider of hydrospatial products and services, has announced the formation of TCarta Canada based in Ottawa, Ontario. Offering the complete line of TCarta satellite-derived bathymetry (SDB) services and Trident SDB Toolbox software, the affiliate office is a partnership between TCarta Marine and Prof. Anders Knudby, a well-known marine geospatial researcher and consultant in Canada.

TCarta made the announcement at the Canadian Hydrographic Conference 2022, which ran on June 9 in Gatineau (Ottawa), Ontario, Canada.

TCarta Canada announced its first contract – a pilot project to update bathymetric navigation charts for Baffin Island’s Cape Hooper and Kangok Fjord with SDB technology. The contract is administered by the Canadian Hydrographic Services, which has previously purchased SDB maps from TCarta.

The partnership between TCarta Marine and Knudby is an ideal merger of complementary technologies. Knudby, who will serve as Managing Partner for the new office, has pioneered development of SDB algorithms for Canada’s coastal waters as a consultant and associate professor at University of Ottawa. TCarta has recently focused on expanding its SDB techniques for application in Arctic regions. Knudby’s algorithms are being incorporated into the TCarta Project Trident SDB workflow.

“TCarta Canada will accelerate our research and push the boundaries for how we deliver marine geospatial products. The Canadian Arctic is an enormous area, difficult to access, often covered in cloud, ice, and darkness, and poorly charted,” said Knudby. “But maritime traffic is increasing as the Arctic Sea ice recedes, and mariners crossing these waters need up-to-date information for safe navigation. TCarta Canada will play an important role here, turning satellite imagery into the information products that mariners need.”

At the heart of TCarta Canada’s offerings will be the new Trident (SDB) Toolbox, now available as a software-as-a-service product. The Toolbox is a series of software applications that operate within Esri ArcGIS Pro and allow organizations to perform their own extraction of bathymetric measurements from satellite, aerial, and UAV imagery.

With offices in the United States and Jamaica, TCarta has built an international business on cost-effectively and safely deriving onshore and offshore data sets using multispectral imagery captured by Earth observation satellites – without negative impact on the natural habitat. TCarta products and services are relied upon by governmental, insurance, oil & gas, environmental, and infrastructure development clients in applications as diverse as natural resource monitoring, tsunami modeling, disaster & hazard response, and hydrologic studies.

View this article here: https://www.oceanbusiness.com/general-ocean-news/tcarta-opens-canadian-affiliate-office-to-provide-hydrospatial-mapping-services-across-canada/

The national land agency in Jamaica has integrated satellite-based hydrography to benefit from time efficiencies, cost savings and improved safety as part of its hydrographic programme in support of the nation’s further economic development.

Central America and the Caribbean region are blessed with beautiful coastal waters. However, most nations, if not all, face the arduous task of developing and managing their natural resources, such as the marine environment, while focusing on economic development. Under the International Convention for the Safety of Life at Sea (SOLAS), Jamaica is responsible for executing hydrographic surveys of its coastal waters. The National Land Agency (NLA), the recognized national hydrographic office, has a hydrographic survey programme in place to cover the bathymetry of Jamaica’s coastal waters in fulfilment of its responsibility to collect, maintain and disseminate nautical information to all its stakeholders. Through a contractual arrangement, Jamaica’s admiralty charts are produced and maintained by the United Kingdom Hydrographic Office (UKHO). The acquisition of refined, reliable and enhanced hydrographic information in Jamaica’s territorial waters supports Jamaica’s development as a nation, tapping further into the blue economy.              

Background to the National Land Agency (NLA)                        

Under the Surveys and Mapping Division (SMD), the NLA is responsible for carrying out hydrographic surveys of Jamaica’s harbours and territorial waters. The NLA is the national hydrographic office recognized by the International Hydrographic Organization (IHO). While operating under resource constraints, as with most small island developing states, the SMD is tasked with surveying Jamaica’s coastal waters. Nonetheless, an intergovernmental agency partnership has been brokered through the National Hydrographic Committee (NHC), resulting in an agreement for the use of a Jamaica Defence Force Coast Guard vessel, which was utilized in the recent survey of Bowden Harbour in St. Thomas.

Port Morant (Bowden) Harbour single-beam sonar bathymetric survey 

The NLA conducted a single-beam hydrographic survey of Port Morant (Bowden) Harbour in December 2020. The purpose of the survey was to collect hydrographic data of the harbour to aid the update of Admiralty Chart number 275-3 and fulfil other hydrographic needs. The survey covered an area of approximately 3.4 square kilometres (340 hectares). The line spacing for the development lines was 20m, which ran perpendicular to the depth contours. Approximately 171 development lines (planned lines) and 43 check lines were generated for the survey area. The survey was carried out over ten days, collecting sonar data from 06:00 to 18:00.

A considerable amount of human and capital resources are required for the execution of a successful traditional single-beam sonar survey (SBSS) or multibeam sonar survey (MBSS). As can be seen in Figure 2, eight people were involved in the data collection for this project. The Jamaica Defence Force Coast Guard provided four boat crew coxswain and boat aids, while the NLA provided four people as part of the data acquisition team.

Collaboration: National Land Agency and TCarta Caribe 

The Bowden Harbour Project presented an excellent opportunity as a case study into the usefulness of satellite-derived bathymetry (SDB) to improve the efficiency of hydrographic surveys, as the SDB data was readily available through TCarta. Additionally, the team wanted to test the potential for SDB to support single beam surveys. TCarta Caribe provided the NLA with the SDB of Bowden Harbour to carry out the investigation. 

TCarta and the NLA also teamed up after the survey for a capacity-building workshop, presented by TCarta, to address three objectives: (1) the SDB’s potential to inform hydrographic survey planning; (2) to describe/explain SDB production methods; and (3) to perform data analysis and comparisons between a single beam derived surface and that of the SDB for Bowden Harbour.

TCarta’s team advised that, as the SDB software is integrated into ESRI in ArcGIS Pro, and as the NLA already uses ArcGIS Pro, it would be a natural progression for the Carta’s NLA to build its marine spatial data infrastructure within this platform.

The workshop continued with a session on the process of producing SDB using TCarta proprietary software, the Multispectral Bathymetry Tool (MBT) in ArcGIS Pro. In addition, the workshop focused on the process involved in the production of SDB in Bowden Harbour and gave an overview of SDB’s feasibility in Jamaica’s coastal waters. The final session zeroed in on the statistical analysis of SDB in comparison to NLA single beam data.  

TCarta used three NLA transect lines, as ground ‘truthing’, for the correction of the SDB data, from which a surface was produced (see Figure 3). A graphic representation of the SDB-derived data is shown in Figure 4, highlighting the usefulness of planning survey lines and mapping areas of caution. 

TCarta SDB vs NLA SBES

The NLA’s GIS unit created a difference map of the single beam echo sounder (SBES) data versus the TCarta SDB data. Preceding the creation of the difference map, TCarta applied a datum adjustment to the SDB, adjusting the SDB depths to the local mean low water (MLW) datum, approximately 0.25m above lowest astronomical tide (LAT). A point-to-point comparison was carried out by the NLA’s team using ArcGIS, analysing 871 congruent points. The results show that 15.39% of the points had a difference of ±0.5m, while 86.80% had a difference within ±2 metres (see Table 1).

With the generation of the difference map, an analysis could be made of the general agreement between the data, cross-referencing these differences with the seafloor topology and identifying possible trends at various depth ranges (see Figure 5). The differences between the NLA SBES data and the TCarta SDB data are shown as spot heights. Positive (+) differences (58.67%) indicate that the SDB data is deeper and negative (–) differences (41.33%) indicate that the SDB data is shallower than the NLA SBES data. 

NLA also analysed ten particular areas with varying seafloor topology. The general trend indicates that SDB data tends to be shallower in deeper water and deeper in shallow water, compared to NLA’s SBES data.

Discussion

The SDB technology was found to give a general indication of the depths within the project area. SDB gradually detects changes in depths; in other words, it ‘smooths’ the changes in depth and will not detect sudden outcrops or rocks. As such, SDB is a useful tool for filling in the gaps. These could be gaps between survey lines with respect to SBES or gaps in depths to the zero-depth contour, which are hard to survey with typical survey vessels, therefore improving on the spatial resolution. SDB is an excellent tool for planning and conducting feasibility studies of traditional bathymetric surveys to be undertaken, especially where inadequate chart data exists.

SDB technology can be a catalyst for the mapping of Jamaica’s coastal waters, which is vital to the blue economy and to further aid our understanding of climate change and other environmental impacts. With the current focus of the region on the Seabed 2030 initiative, which aims to survey the ocean floor by the year 2030, there is much demand for bathymetric data in the region. The current pandemic has seen already limited resources being diverted to the health sector, and those resources that are allocated to the marine environment must be used as efficiently as possible. Some countries have also seen the limited mobilization of hydrographic survey teams, to reduce costs as well as to reduce the spread of COVID-19. Collaborative approaches, such as the integration of SDB with traditional survey methods, is one approach that can aid the realization of the Seabed 2030 initiative. 

The integration of satellite-based hydrography, which promotes time efficiencies, cost savings and improved safety, lends itself to the development of the NLA’s hydrographic programme. This collaboration and integration of technologies goes hand in hand with the NLA’s commitment to research and development.

Conclusion

SDB is a quick and inexpensive way to obtain a general idea of depths for applications such as fisheries and post-disaster response and rescue planning. It can be used as a tool for planning and conducting feasibility studies of traditional bathymetric surveys, but the vessel should navigate with the utmost care where the underkeel clearance is calculated to be less than five metres.

View this article here: https://www.hydro-international.com/content/article/satellite-derived-bathymetry-for-surveying-jamaica-s-coastal-waters

AI expands reach of SDB

Satellite-derived bathymetry (SDB) technology has been improved and applied more substantially in the past three years than in the previous two decades,  primarily due to increasingly accessible machine learning algorithms, scalable computing power, a multitude of satellites orbiting the Earth and a new source of validation data. Today, SDB is applicable in water conditions and geographic areas once considered entirely unsuitable for the technology.

Credit for these recent advancements must also be attributed to funding by the U.S. government. In 2018, the National Science Foundation (NSF) awarded a Small Business Innovation Research (SBIR) grant to TCarta Marine of Denver, Colorado, to initiate Project Trident. Its goal was to leverage machine learning to expand SDB beyond clear, calm waters into more dynamic, turbid coastal environments. [Project Trident was described in the June 2020 issue of Sea Technology.]

As several key components of the research came to fruition, TCarta set its sights on Alaska. SDB had rarely been applied successfully in this state due to a combination of factors, of which water clarity is just one. The National Oceanic and Atmospheric Administration (NOAA) awarded SBIR grants to TCarta in 2020 and 2021 to adapt and modernize SDB techniques and incorporate new sensor capabilities for Alaska and the Arctic region. 

This article describes the latest progress from Project Trident and the current state of play for SDB in northern latitudes.

What is SDB?

SDB technology extracts water depth measurements from satellite imagery at lower cost and with fewer restrictions than ship-borne sonar or airborne LiDAR. SDB algorithms are applied to what is called ‘multispectral’ optical satellite imagery. Multispectral means the onboard sensor measures natural energy reflectance from features on the Earth’s surface in many wavelengths, usually visible Red, Green, and Blue, as well as near infrared. 

SDB is now a commercial technology, and TCarta routinely generates SDB products with bathymetric point values spaced less than a meter apart on the seafloor to depths of 20 meters, depending on water clarity and turbidity. In extremely clear water, measurements down to 30 meters are reliably produced. The accuracy of these data sets is typically 10-20% of water depth.

Enhancing SDB with ML and ICESat-2

SDB processing of multispectral imagery has primarily involved application of two algorithms – Band Ratio and Radiative Transfer. Both are mathematical calculations that rely on visible light passing through the water column and reflecting off the seafloor. The drawback, of course, has always been the fact that light doesn’t penetrate murky, sediment-loaded waters in many dynamic coastal environments. 

With the NSF-funded Project Trident, TCarta saw supervised machine learning (ML) as a solution to this problem on many fronts. Explained simply, supervised ML uses verified training data to teach the computer to recognize similar features or patterns in other comparable data sets. It is important to note that the current ML renaissance has been made possible by widespread and affordable availability of the massive computing power required to run the iterative ML algorithms in reasonable periods of time. 

The underlying premise of Project Trident was that coastal zones known for their cloudy, turbid waters traditionally deemed unsuitable for SDB likely experience at least a few days of water clarity each year. It was simply a matter of collecting satellite imagery, or finding imagery already acquired, on those rare days.

This is where imagery from the European Sentinel-2 satellite came into play. This satellite collects imagery constantly, building an archive of hundreds of images for each spot on the Earth’s surface since its 2015 launch. More importantly, the data is available globally for free. 

TCarta technicians created ML-based software to automatically search the Sentinel-2 archive and select those coastal images with water quality appropriate for SDB. The same filtering could be accomplished with the naked eye but would literally have taken years compared to what ML can do in minutes in the cloud or on a computer equipped with an AI-capable graphics processing unit (GPU).

The automated ML image filtering was a success and, in many cases, returned not one, but dozens or even hundreds of suitably clear images. With the capability to analyze the full archive of available imagery, TCarta’s technicians found a substantial advantage  when the ML method  was scaled to use not just one good image, but to identify suitable individual pixels within multiple images that could be used for SDB processing. These filtering techniques are referred to as pixel-wise and image-wise.

TCarta remote sensing scientists also worked on enhancing the SDB process itself. The team customized a common ML-based decision tree algorithm called Random Forest and adapted it for extraction of water depths from the multispectral images. Random Forest thus became an SDB calculation complementary to Band Ratio and Radiative Transfer. 

The Colorado firm then upended the entire SDB workflow. Rather than apply one algorithm to a single satellite image, they created composite images of the best pixels. Then they leveraged the power of cloud computing to process multiple SDB algorithms on every suitable pixel selected by the filtering. This meant dozens of water depth calculations were typically made for each point on the seafloor that was visible in the imagery. 

Highly accurate bathymetric values were then determined by combining the results of the multiple calculations.  While initially developed and deployed on Sentinel 2 imagery, these same techniques and methods can be applied to any optical imaging satellites

Enter ICESat-2

An addition to the SDB workflow came with the 2018 launch of the NASA ICESat-2 (Ice Cloud & land Elevation) satellite carrying a laser altimeter, or LiDAR, designed for measuring the thickness of sea ice, glaciers, and tree canopies. The ICESat-2 data proved extremely adept at determining elevation points for the seafloor at 0.7-meter intervals with centimeter-level accuracy to depths of 30 meters. Although not applicable for broad-area mapping due to the large gaps between measurement lines, this free data was ideal as a ground truth data set for Project Trident and scalable and global extraction and application of these data may be the single most important SDB technology breakthrough of the research. 

TCarta integrated the satellite LiDAR data into its SDB workflow in two important ways. First, ICESat-2 bathymetric measurements were employed as training data sets for the ML-based Random Forest algorithm. Then after the elevation extraction processing was complete, the team used ICESat-2 points to validate the accuracy of overall SDB calculations, reducing uncertainty in derived water depth values. 

As a result of Project Trident, TCarta has generated bathymetric maps for coastlines where water conditions had traditionally thwarted SDB application. These areas include the Korean Peninsula, Greenland, Arctic Canada, and New England in the U.S. The depth and accuracy of these locations can now equal those that SDB has previously delivered in clear, calm water. 

The research culminated in the launch of a new Global Satellite Derived Bathymetry (G-SDB) product extracted from Sentinel-2 and ICESat-2 data. G-SDB data set contain bathymetric measurements from 0-20 meters generally and up to depths of 30 meters, depending on water clarity, at 10-meter resolution. The depth values for every 10-meter pixel are the combined result of numerous measurements, resulting in accuracy within 10% of depth or less. G-SDB will be available globally for all oceans and seas, as well as large freshwater lakes where water conditions permit. 

Applying the results of Project Trident, the Office of Coast Survey at NOAA contracted TCarta to deploy the technology to produce 2m resolution SDB using WorldView imagery for two historically difficult areas of Western Lake Michigan and around Cape Cod and Nantucket Sound, where natural forces alter the underwater terrain faster than traditional bathymetric surveys can be completed SDB is being considered as a fast and inexpensive alternative for such coastal zones.

Fine Tuning SDB for Alaska

Mapping Alaska’s coastal waters became a priority for NOAA in December 2019 with the issuance of a Presidential Memorandum which resulted in the development of the Alaska Coastal Mapping Strategy and cites SDB as a key technology for surveying the 32,000 miles of Alaskan shoreline.

In 2020, NOAA awarded an SBIR grant to TCarta to research and deploy multiple SDB techniques and approaches for Alaska. The Arctic region was considered almost impossible for SDB implementation due to a multitude of factors. Coastal waters there are extremely dynamic, carrying excessive sediment loads, not to mention sea ice, nearly year-round. Additionally, six months of darkness and frequent cloud cover thwart image collection by optical satellites. 

The goal of the NOAA Phase II grant is to determine how best to deploy SDB techniques in Alaska and if the ML algorithms and pixel-wise filtering techniques can be refined for use with higher-resolution commercial imaging satellites in Arctic waters. Even more ambitious, TCarta scientists hope to create composite bathymetric surfaces composed of the best combined pixels from multiple different satellite sensors. 

In the first phase of the research, the project is focused on determining when is the optimal time to capture imagery for the most accurate SDB surfaces and comparison of accuracy across multiple optical satellite sensors.      

Timing of imagery collection with the tidal phases is paramount in Alaska due to the significant range and because the best images for use in SDB are captured in sync with incoming tides. This is preferable because the maximum tidal zone is exposed and the water is shallow farther out, allowing SDB to measure depths at a greater distance from the shore. The incoming tide typically has better clarity because it brings in clearer ocean water and typically carries less sediment runoff from the land. 

The second phase of the Alaska research is to determine when – or if – optical imagery suitable for SDB processing has been or will be acquired for coastal Alaska. Between the tidal and environmental conditions, TCarta knows the likely collection window is so small that it will not find a treasure trove of hundreds, or even dozens, of appropriate images in existing archives. 

To increase the chances of obtaining the necessary high-quality imagery, TCarta is once again applying its ML-based search capabilities to review images and individual pixels acquired by high-resolution optical satellite programs: MAXAR’s WorldView and Planet’s SkySat, most notably. They are also beginning to incorporate hyperspectral imagery – covering broader wavelengths – from Satellogic, a new provider in commercial remote sensing. 

The remote sensing scientists realize they may end up with a combination of SDB-worthy images and pixels from multiple sensors to process together to calculate water depth in small coastal areas. 

With this in mind, TCarta had developed a process to assimilate radiometric response to compensate for sensor differences among the various satellite systems. This will enable the ML filtering algorithms to make apples-to-apples comparisons between Planet, Satellogic and WorldView pixels, for example. Assimilation will also be required when SDB processing is applied to stacks of pixels from multiple different satellites. 

TCarta is confident that it will make significant headway in determining which satellite sensors, or combinations thereof, have the greatest potential for capturing SDB-quality data. Moreover, the researchers also expect to have begun piecing together a predictive schedule of when the image acquisitions should occur for specific parts of the Alaskan coast. Optimism is tempered by the possibility that suitable images will never be acquired for some areas due to extreme conditions.

Where applicable images – or pixels – are acquired, however, TCarta plans to begin processing them in the refined Project Trident SDB workflow by summer 2022. Again, optimism is modest with expectations suggesting that SDB, if it is successful at all, may produce results in depths of only 8-12 meters and limited to 3-5 meters in some locations. 

There will remain areas where clear water conditions never exist. But these data and information results will have a high degree of confidence and will represent an improvement over what is available now for many coastal zones.

A secondary, yet important outcome of the Alaska research is that by using information from multiple satellites, TCarta will be able to predict when and where coastal water clarity is best in the state on a daily basis. The Colorado firm has plans for a web portal for accessing these insights in support of NOAA’s hydrographic surveying operations so it can better plan where to deploy LiDAR mapping aircraft in the region. LiDAR, like SDB, depends on clear water for highly accurate subsurface data collection. 

There is no one best solution for surveying coastal water, particularly remote and dynamic areas like Alaska but by combining the recent advancements in SDB technology with the new and next generation space-based sensors along with machine learning and cloud computation, there is great potential for SDB to address in part the challenge of surveying coastal waters in Arctic conditions.

Through both the broad and automated approach to global SDB that TCarta developed under Project Trident and the precision collection and combination of sensors for Alaskan waters, TCarta has developed and deploying a multitude of next-generation approaches to Satellite Derived Bathymetry to address the global need for coastal bathymetry.

View this article here: https://lsc-pagepro.mydigitalpublication.com/publication/?m=60787&i=710019&p=8&ver=html5

TCarta Marine, a global provider of marine geospatial products, has supplied the National Oceanic and Atmospheric Administration (NOAA) with satellite-derived bathymetry (SDB) validated by green laser altimeter data from the NASA ICESat-2 satellite for two U.S. shallow-water coastal areas.

TCarta was the subcontractor on the prime contract awarded to Woolpert, an international geospatial firm headquartered in Dayton, Ohio.

The NOAA pilot focused on two shallow-water regions that were 3,000 square kilometres in total area – one in the Green Bay area of western Lake Michigan and the other around Cape Cod and Nantucket Sound. Both areas experience natural forces that alter the underwater terrain faster than traditional bathymetric surveys can be completed.

SDB is being considered as a fast and inexpensive alternative for such coastal zones. A primary advantage of SDB is that orbiting satellites can be tasked to collect up-to-date imagery, with bathymetric measurements derived to create end products in a matter of days.

Airborne Lidar and Marine Sonar

TCarta created products in the two project pilot areas to enable NOAA to test the use of SDB in shallow coastal zones. This provided updated bathymetry and infilled data gaps from traditional bathymetric measurement technologies, such as airborne Lidar or marine sonar. The pilot was conducted jointly by NOAA’s Office of Coast Survey and National Geodetic Survey’s Remote Sensing Division. The SDB datasets measured the seafloor to a depth of 20–25 metres, with validation using ICESat-2.

“The integration of ICESat-2 bathymetry with satellite imagery-derived bathymetry is a powerful combination to increase accuracy,” said RDML Shepard Smith, the recently retired director of NOAA’s Office of Coast Survey. “It holds the potential to dramatically improve our ability to monitor change in dynamic coastal waters and allow us to map remote areas for the first time.” 

“The enhanced SDB product validated with ICESat-2 data created for this pilot results directly from our research under the National Science Foundation SBIR programme,” said TCarta president Kyle Goodrich.

In late 2019, TCarta received a Phase 2 Small Business Innovation Research (SBIR) grant to commercialize next-generation SDB measurement technologies. ICESat-2 (Ice, Cloud & land Elevation Satellite) space-based laser data was included in the research following the satellite’s launch in 2018.

View this article here: https://www.hydro-international.com/content/news/tcarta-delivers-satellite-derived-bathymetry-for-u-s-coastal-mapping-pilot#:~:text=TCarta%20created%20products%20in%20the,airborne%20Lidar%20or%20marine%20sonar.

TCarta Marine, a global provider of space-based hydrospatial solutions, has been awarded a Small Business Innovation Research (SBIR) Phase II grant from the National Oceanic and Atmospheric Administration (NOAA). The research focuses on enhancing Satellite Derived Bathymetry technology for application in the coastal waters of Alaska.

Satellite Derived Bathymetry (SDB) extracts water depth measurements from multispectral satellite imagery using advanced physics-based algorithms. Traditionally, this technology has yielded the most accurate results in clear, calm waters; however, TCarta has recently taken the lead in expanding SDB applications to more challenging marine environments worldwide.

“With the NOAA SBIR grant, our objective is to explore what SDB can achieve in Alaska’s coastal waters with the expectation of applying our findings to the greater Arctic region,” said TCarta President Kyle Goodrich. “This research will benefit hydrographic surveying, coastal zone management, infrastructure development, and other coastal marine projects at high latitudes.”

Begun in 2020, the NOAA SBIR Phase I research expanded the potential sources of satellite imagery for the Alaskan coast. Winter darkness, floating sea ice, turbulent spring runoff, plankton blooms, and unpredictable tidal variations make it difficult to capture images with the quality necessary for SDB processing. Just a small window of acquisition time exists during the summer, and it varies for different areas along Alaska’s 32,000 miles of coastline.

“By analyzing data captured with several types of satellite sensors, including multispectral, hyperspectral, green laser, and synthetic aperture radar, we are determining which images and methodologies – or combinations – produce the optimal characteristics for SDB,” said Goodrich. “This is helping us devise a tasking strategy to capture Alaska imagery at the right time with the right sensors.”

An important Phase I result was the development of automated tools to assess water clarity in daily satellite images to monitor water clarity for suitable conditions for SDB image tasking or planning airborne LiDAR surveying, Goodrich added.

In Phase II of the NOAA program, TCarta has shifted focus to SDB data processing and hydrographic analysis by developing new ways to improve confidence in the seafloor depth measurements derived from Alaskan imagery. The Colorado firm is creating workflows involving Artificial Intelligence to identify and minimize errors in SDB measurements, predict uncertainty and to integrate established hydrographic standards, thereby enhancing interoperability of SDB with other technologies.

“By the start of summer 2022 collection season, we will have developed a multi-satellite coastal surveying capability and a collection strategy for maximization of these technologies in Alaskan and Arctic waters,” said Goodrich.

View this article here: https://lidarmag.com/2021/03/08/tcarta-awarded-noaa-grant-to-enhance-satellite-derived-bathymetry-technology-in-alaskan-waters/