EMODnet DTM for European sea regions
A harmonised EMODnet Digital Terrain Model (DTM) has been generated for European sea regions (36W,15N; 43E,90N) from selected bathymetric survey data sets, composite DTMs, Satellite Derive Bathymetry (SDB) data products, while gaps with no data coverage are completed by integrating the GEBCO Digital Bathymetry.
The DTM with its information layers is made freely available for browsing and downloading through the Bathymetry Viewing and Download service.
In October 2016 a version of the EMODnet DTM had been released with a grid resolution of 1/8 * 1/8 arc minutes. In the meantime, more survey data sets have been gathered from an increasing number of data providers and activities have been undertaken for correcting identified anomalies, where possible. This has resulted mid September 2018 in the release of a new DTM, now with an increased grid resolution of 1/16 * 1/16 arc minutes (circa 115 * 115 meters).
End 2020 further progress has resulted in the latest 2020 DTM release, continued with a grid resolution of 1/16 * 1/16 arc minutes, while the number of underlying bathymetric surveys and composite DTMs has been expanded from circa 9400 in the 2018 edition to circa 16360 in the latest 2020 edition. The 2020 DTM data product is freely available to users as GIS layers for viewing, while the DTM versions from 2016, 2018, and 2020 are also available for sharing as OGC web services (WMS, WFS, WMTS, WCS) and downloading as DTM tiles in several output formats. The DTM cells contain references to the data sets as used by CDI references for survey data, Sextant references for composite DTMs or alternatively a reference to GEBCO and IBCAO in case no data was available.
The geographical boundaries of the 2020 DTM service are set to: N90 W36 and N15 E43. The geodetic system for the grid is chosen as WGS84. The EMODnet DTM is generated by regional teams from the EMODnet Bathymetry partnership.
All regional teams follow a common QA-QC process and DTM generation methodology.
Users can activate and view the various information layers.
Users can zoom in/out and switch on/off several layers. Per DTM cell users can call up and browse the data as specified in the QA/QC documentation including retrieving metadata about the underlying data source. Users can draw transects and retrieve the bathymetric profile along that transect. Moreover users can download the DTM data in several output formats, in ASCII CSV, ESRI ASCII, NetCDF (CF), GeoTIFF and Fledermaus SD files. The downloading of the DTM is done in large tiles that users have to select. For the 2016 version there are 16 tiles, while the 4 times larger 2018 and 2020 versions are downloadable in 64 tiles.
Online 3D viewing service: 3D visualization functionality has been added to the bathymetry viewing that can be used in the browser without requirement of plugins. The 3D application is based on Cesium. However a dedicated data structure has been developed by EMODnet Bathymetry based on a triangulated irregular network (TIN). Having a TIN instead of a regular grid enables faster representation of the complexity of the map (i.e. the number and size of triangles). Software has been developed to create tiles in quantized mesh format out of a raster format such as used in EMODnet DTM. A report about the approach can be downloaded while the software is made available at GitHub.
Offline 3D Viewer: the DTM files of the 2018 version in NetCDF format can also be visualised by using the 3D visualisation tool (3D Viewer) that has been developed in the EU FP7 Geo-Seas project. This viewer is based on the existing open source NASA World Wind JSK application. This software is freely available after registration and allows the visualisation of Digital Terrain Models (DTM) in the existing GLOBE NetCDF format and Web Map Service (WMS) which are plugged into a virtual globe. More info about the GeoSeas 3D viewer and link to the registration page can be found here.
The 2020 DTM version tiles are available in NetCDF V4, which is not supported by the Geo-Seas offline viewer, but can be visualised with the Globe software of IFREMER. More info about Globe software can be found here.
The SD files can be visualized with Fledermaus 3D viewer software.
The DTM information layers are also provided as OGC web services which allow machine-to-machine exchange with other web portals.
EMODnet Bathymetry World Base Layer (EBWBL) – WMTS service
In 2020, EMODnet Bathymetry has also produced and released a first edition of its World Base Layer (EBWBL) service, which is only made available as OGC WMTS service. This World Base Layer provides a gridded representation of worldwide bathymetric and topographic coverage adapted for a better representation of seabed morphological features. Based on modern WMTS schema, it allows a fluid and powerful rendering.
For the global oceans, EBWBL is composed of the 2018 EMODnet Bathymetric grid around Europe (approx. 115m resolution) and uses the GEBCO 2019 grid (approx. 500m resolution) elsewhere in the marine environment. Land coverage is based on a combination of 30 arc second ASTER GDEM, SRTM3, EU-DEM, and Global 1 second world-wide water body map for the topographic part. The compilation and void filling of the land DEM is based on the work of ViewFinderPanoramas.org. This compilation of publicly available data sources have been merged and pre-tiled for rendering, at 10 levels of zoom starting from 1/24th of an arcminute (approx. 75m resolution). The EBWB1 service is available in non-projected coordinate system (Lat, Long, WGS84: EPSG 4326), Web Mercator (EPSG 3857), Inspire compliant ETRS-EALA projection (EPSG 3035) and projections adapted to both poles (ESPG 3031 and 3996).
The EMODnet Bathymetry World Base Layer provides an easy to use facility for all GIS users or WebGIS designers to get access to the current highest resolved topographic and bathymetric world-wide layout. One can get access to it by following this link:
This site gives details about the WMTS Capabilities document and a Demo Viewer to try out a number of EMODnet DTM layers for Europe, the EBWBL for global coverage, and the various projections supported in the EBWBL WMTS service. The EBWBL layer has also been included in the layer menu of the Bathymetry Viewing and Download service.