Hartmann, Knut

Heege, Thomas

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Article, Published VersionHartmann, Knut; Heege, ThomasHydrographic remote sensing made in GermanyHydrographische NachrichtenVerfügbar unter/Available at: https://hdl.handle.net/20.500.11970/107812Vorgeschlagene Zitierweise/Suggested citation:Hartmann, Knut; Heege, Thomas (2020): Hydrographic remote sensing made in Germany.In: Hydrographische Nachrichten 116. Rostock: Deutsche Hydrographische Gesellschafte.V.. S. 48-51. https://doi.org/10.23784/HN116-07.Standardnutzungsbedingungen/Terms of Use:Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichendenNutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, dieWeiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung derNamensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigenNutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte.Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license isapplicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the materialof the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms ofthe restrictive license will be binding.48 Hydrographische NachrichtenRemote sensingvisually identified patterns and shoals from the first satellite imagery. However, it took almost two dec-ades before satellite-derived information found its way into hydrographic applications. In the mid 80s the French Hydrographic Office SHOM digitised shoals from satellite data and integrated those into nautical charts, known as »spatiocartes«, which represents the beginning of hydrographic remote sensing. At that time satellite sensors, computa-tional power and also analytical algorithms were not made to upscale the process and must be considered as crude compared to modern stand-ards (Fig.  1). It required the continuous, iterative improvement and R&D breakthroughs on all these aspects to achieve impactful progress on hydro-graphic remote sensing. The developments on physics-based shallow water mapping in Germany started in 1998, at the German Aerospace Center (DLR) with Thomas Heege as research scientist, and few years later in Australia with Magnus Wet-tle at CSIRO.It took then until 2014 before the UK Hydro-graphic Office (UKHO) integrated satellite-derived bathymetric information in British Admiralty charts of southern Antigua, almost three decades after the first spatiocartes were published. In many respects this was a milestone in HRS. It was the first time that quantitative bathymetric information from satel-lites, known as satellite-derived bathymetry (SDB; cf. Hartmann et al. 2017), was integrated into charts and the satellite-derived survey was embedded into a combined survey strategy with acoustic sur-veys. The hydrographers showcased that this inte-grated survey concept increases survey efficiency and supports the safety of navigation. More re-cently this concept was taken up to map the Pacific states of Tuvalu and by the New Zealand Hydro-graphic Office (LINZ) to update charts on Tonga. In parallel satellite-derived bathymetric information Some definitions firstOne may argue that remote mapping the sea-bed and other ocean parameters is a standard procedure to surveyors and hydrographers. The mapping of seabed by acoustic methods or air-borne LiDAR can be seen as such remote map-ping, as they survey depths and seafloor proper-ties from a distance. However, these methods still require physical presence of equipment and staff at the survey area. A new level of ›remoteness‹ is achieved if the altitude of the sensor platform is increased significantly, by satellite-mounted sen-sors orbiting the Earth at approximately 750  km altitude. Since the launch of the US Landsat pro-gram in the early 70s satellite remote sensing often stands synonymous for remote sensing – or Earth Observation – and will be used in this article in this way. Nowadays there are numerous satellites of various specifications and designed for multiple needs, from communication to positioning. Re-mote sensing uses those sensors, which have the ability to actively or passively record the composi-tion of the media between sensor and surface. In other words, to record the properties of the earth surface or atmosphere. Most of the HRS applica-tions use data from sensors which either record the returned reflectance of the sunlight (passive sensors), or actively emit a signal and measure its return (active sensors). Generally, the concept of satellite remote sensing has the big benefit to map extended areas without the need to mobilise equipment and staff, and the disadvantage of high requirements on data analytics to correct for quite a lot of environmental error sources.The hydrographic remote sensing history in a nutshellThe origins of hydrographic remote sensing may date back to the early 70s when researchers first An article by KNUT HARTMANN and THOMAS HEEGEWhat links hydrography and remote sensing? What has been developed and integrat-ed in practice? This article addresses these issues with a core focus on the German contribution to hydrographic remote sensing (HRS).Hydrographic remote sensing made in GermanyHRS – hydrographic remote sensing | earth observation | SDB – satellite-derived bathymetryHydrographische Fernerkundung | Erdbeobachtung | SDBDOI: 10.23784/HN116-07AuthorsDr. Knut Hartmann is COO at EOMAP in Seefeld, Germany.Dr. Thomas Heege is CEO at EOMAP.hartmann@eomap.deWas verbindet Hydrographie und Fernerkundung? Welche Möglichkeiten ergeben sich und wie wurden diese bisher umgesetzt? Dies sind die Themen dieses Artikels – mit einem Fokus auf den deutschen Bei-trag zur Hydrographischen Fernerkundung.HN 116 — 06/2020 49Remote sensingfound its way to different applications, which are outside the standard domain of hydrographic ap-plications. The data are being used by survey and offshore industry in almost daily use, and found in the harmonised European bathymetric grid of EMODnet bathymetry and the global grid of  GEBCO. In all these mentioned projects – except the SHOM spatiocartes – the evolving German expertise, with intense involvement of EOMAP, played a major role. Without systematic long-term developments, the current status of hydrographic remote sensing would be different.Quo vadis hydrographic  remote sensing?As shown, the development of hydrographic re-mote sensing was initially slow but had an almost exponential increase of R&D progress and data up-take. Other concepts and products have been de-veloped in the last years which contribute to the hydrographic knowledge as well. To name only a few:• The German Aerospace Centre in Bremen de-veloped solutions to measure wave height from radar satellite data for nearshore sites.Fig. 1: Time-lapse of the development of hydrographic remote sensing. In the early 80s satellite data were analysed with intense man power efforts and required the best processing capacities which were available at that time. Nowadays analyses are done in operational software workflows with processes being directed to graphic cards and cloud environments. Dedicated conferences deal with this former niche topic of hydrographic remote sensing and data are integrated in different hydrographic and related applicationsFig. 2: A small subset of the Great Barrier Reef mapped by satellite data. The brownish areas represent reef crests and plateaus with the blueish colours deeper areas of the atolls which are mainly dominated by coral rubble and sandy bottom. The satellite-derived bathymetric data are shown as hillshaded effects80s 202050 Hydrographische NachrichtenRemote sensingand upscale the complex data analysis of satellite-derived aquatic information, or the integration of satellite-derived information in hydrographic practice, which was addressed in the MARSAT project. With respect to new satellite capabilities we see potential in the current and future micro satellite fleets which are equipped with radar and opti-cal sensors. Those constellations allow multiple recordings per day and if combined with pro-grammatic interfaces will have their strength in improving the knowledge, especially for maritime surveillance. Furthermore, the recent US satellite IceSat 2 supports the satellite bathymetric map-ping. It holds a green photon-counting LiDAR with a 10 kHz pulse repetition rate, which records the earth in regular but sparse tracks. Although the instrument was not intended for bathymetric analysis. the data can be used in this way and – in combination with satellite-derived bathymetric data from multispectral information – allow a fur-ther improvement of the mapping and surveying from space (Fig. 4).And last but not least, next to various commer-cial satellite providers which will launch satellites in the next years, also the European Space Agency will double the number of its very impactful mul-tispectral Sentinel-2 satellites from two to four in the next years. All that leads to the fact that the amount of satellite remote sensing data continu-ously increases. But satellite data are worthless without the capability to analyse them and bring them into value. Thus, with respect to new al-gorithm packages and data integration we see recent and future advances in increasingly auto-matic analysis of satellite data for the offshore in-dustry and hydrographic entities. We believe that this trend will continue and, thanks to decades of sound algorithm developments, the hydrographic • Deltares in the Netherlands published a global analysis on shoreline dynamic using optical satellite data.• In Australia the habitat and morphology of the world’s largest reef system, the Great Barrier Reef which comprises approximately 10 % of the global corals, was mapped in high detail for the first time (Wettle 2019) (see Fig. 2).• The German Baltic of Schleswig-Holstein made use of the same concept to map the benthic environment (Hartmann et al. 2019).• The mapping of satellite-derived global water quality parameters was released in 2019 (UN-ESCO 2018; SDG6 2020).• Drift and Noise, based in Bremen, provides satellite-derived ice information to increase efficiency and safety of navigation in higher latitudes.So, what is next? We believe that the cycle of improvement on sensor technology, process-ing capacities and algorithm developments will continue, and lead to further significant improve-ments and also increased integration of all those into workflows of the hydrographic community. To name just a few examples, current activities of EOMAP focus on developing integrated survey concepts of autonomous underwater vehicles and satellite-derived bathymetric data (Syrius project, co-funded by the European Space Agency), and to transfer and combine the strengths of satellite-data analysis with airborne drones (see Fig. 3).Again, we see Germany well positioned with those developments. Thanks to the innovation co-funding of Federal Ministry of Transport and Digital Infrastructures, current activities are focus-ing on multi-temporal data processing on FGPAs (field programmable gate arrays) and graphic cards (SDB2030 project) to reduce uncertainties Fig. 3: Combining drone- and satellite-analysis for mapping shallow water environments. The example shows an area of approximately 250 × 250 m in Belize and represents depth at 9 cm spatial resolution overlaid with a realcolour image which shows the different seafloor types from bright sand to coral and hardbottom areas (top left) to sparse to dense seagrass areas (lower right and centre)Image courtesy: EOMAP GmbH & Co. KG, 2020HN 116 — 06/2020 51Remote sensingcommunity will increasingly make use of hydro-graphic remote sensing solutions. This develop-ment runs in parallel with the development of cloud processing platforms such as the Google Earth Engine, Amazon cloud or European DIAS centres which are capable to speed up big data analytics to an amazing degree – as long as the implemented data analytical capabilities provide the base with robust information products.ConclusionHydrographic remote sensing has performed an impressive rise in the last years and satellite-derived information is used in multiple applica-tions and programs nowadays. The journey will continue and innovations are being developed on different levels, which altogether will provide more precise and up-to-date spatial information for hydrographers and the offshore stakeholders. We see Germany with its strength in the maritime industry and engineering and remote sensing ex-pertise well positioned to continue being a lead-ing nation in this topic. //Fig. 4: A: Bathymetric grid derived from multispectral satellite-derived bathymetry analysis. The map shows a 10 m dense bathymetric grid for Tetiaroa atoll. B: Orange dots represent track lines of the IceSat 2 photons which were returned by the seafloor. C: Scatterplot of data shown in A and B. Combining both methods allows to define the vertical uncertainties more precisely and improve overall accuracies without being on siteImage courtesy: EOMAP GmbH & Co. KG, 2020Big thanksHydrographic remote sensing made in Germany would not have been possible without the excellence and passion of individuals and the fertile environment for developing in-novations. That said, we at EOMAP have to be thankful for the support given to us all these years by the DLR Space Agency and the innovative state governments implementing these new data services: we would like to name Schleswig-Holstein in special. We wish to highlight the passion brought into this topic by Peter Dugge (Atlas Elektronik), Dr. Marco Filippone (Fugro Germany) and many others who all surely contributed to pushing the limits of HRS.ReferencesHartmann, Knut; Thomas Heege et al. (2017) Satellite-derived bathymetry. An effective surveying tool for shallow-water bathymetry mapping. Hydrographische Nachrichten, DOI: 10.23784/HN108-05Hartmann, Knut; Kim Knauer et al. (2019). Aus der Ferne in die Tiefe. Kartierung der Schleswig-Holsteinischen Ostsee durch Satellitendatenanalysen. Hydrographische Nachrichten, DOI: 10.23784/HN113-09SDG6 (2020): SDG Reporting Portal. http://sdg6-hydrology-tep.euUNESCO (2018): UNESCO launches a pioneering tool to monitor water quality. https://en.unesco.org/news/unesco-launches-pioneering-tool-monitor-water-qualityWettle, Magnus (2019). The Great Barrier Reef and the Evolution of Satellite-Based Mapping. ECO Magazine. http://digital.ecomagazine.com/publication/?i=637008&article_id=3538296&view=articleBrowser&ver=html5

Hydrographic remote sensing made in Germany

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Hydrographic remote sensing made in Germany

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