About the BSBD data
Source data
Each Baltic Sea country’s territorial waters and Exclusive Economic Zone (EEZ) is based on data sets provided by the respective national hydrographic authority. Some of these data sets are publicly available, and some are only provided to BSHC for the compilation of the BSBD model.
See data sources for more details.
How this data set is produced
The source data is gridded using the method "Stacked continuous curvature splines in tension". Basically it works like this:
- Within each grid cell, all data points are median filtered, keeping only one point corresponding to the median depth in the cell.
- With these data points as input, a continuous surface is calculated with one value for every grid cell, using a spline in tension algorithm. This surface connects the data points and interpolates values for cells devoid of data.
- Depending on the source data density in each place, interpolated grid cells with too bad data support (i.e. too far away from the next data points) are deleted.
- In order to fill these still-empty cells, the entire gridding process is repeated, but on a grid with doubled cell spacing. With the larger grid cells the data support is better and more areas are being interpolated.
- The process is repeated until the entire area is filled, resulting in a series of coarser and coarser grids with fewer and fewer holes.
- In a last step, all the grids are stacked together, with smaller grid cells taking precedence over larger ones.
The source data density grid displayed in the map shows which gridding resolution each cell originates from. Dark green cells have been gridded at the native resolution (500m), whereas yellow, orange and red cells originate from coarser grids. A little simplified, the source data density grid shows approximately the distance between the source data points used for the compilation.
Color scale
Bathymetry
| >500m | 500m – 250m | 250m – 100m | 100m – 25m | 25m – 0m | 0m |
| −500m | −250m | −100m | −25m | 0m |
Source data density
| 500m | 1km | 2km | 4km | 8km | 16km | 32km | 64km |
Downloadable data formats
ASCII .xyz
Space delimited XYZ-ASCII Format with the columns longitude, latitude and depth in meters. Latitude an longitude are formatted in decimal degrees with decimal point. The records are separated by Unix style end-of-lines.
Arc ASCII grid
Standard text-based grid format developed by ESRI. You can find a format description on Wikipedia. The file extension is .grd and is supported by Arc-Map version 9.6 and later. For support in earlier versions of Arc-Map please change the file extension to .asc after download.
32bit floating-point GeoTIFF
Single-channel GeoTIFF data, featuring depth as 32bit floating point numbers.
RGB PNG
PNG image, showing a colored and shaded relief of the BSBD model as well as a shaded relief of land elevations. You should be able to view these files in your web browser and most image viewing programs.
RGB GeoTIFF
3-channel RGB GeoTIFF image, showing a colored and shaded relief of the BSBD model as well as a shaded relief of land elevations.
Positioning, projections and vertical reference
Positioning and projections
The map view is presented in EPSG:3035 ETRS89/LAEA projection. All data downloaded from the map comes in unprojected geographic (latitude/longitude) coordinates in EPSG:4258 referencing to ETRS89.
The OGC services provide additional spatial reference systems. See the GetCapabilities output of the WMS for an authoritative list.
Vertical reference
The vertical reference in this project is EPSG:5730, EVRF2000. The horizontal and vertical combination is also referred to as EPSG:7409.
More information
See the spatial reference systems page.
INSPIRE
INSPIRE compliant metadata records for the Baltic Sea Bathymetry Database is available at: