Bathymetric attributed grid

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Bathymetric Attributed Grid (BAG)
Icon and logo for the Bathymetric Attributed Grid (BAG) format
Filename extension.bag
Developed byThe Open Navigation Surface Working Group
Latest release
November 1, 2022; 13 months ago (2022-11-01)
Type of formatScientific data format
Open format?Yes

Bathymetric Attributed Grid (BAG) is a file format designed to store and exchange bathymetric data.

The implementation of the format was triggered by the large adoption of gridded bathymetry and the need of transferring the required information about bathymetry and associated uncertainty (i.e., metadata) between processing applications. The BAG format was designed to provide a container able to transfer all of the relevant information of a given bathymetric project. The creation and the access to the format is supported through a code base implemented in C++.[2][3]

The format is supported by The Open Navigation Surface Working Group whose mission is to ensure its continued development.

The format can be accessed using GDAL, currently in read-only mode.[4]

NOAA NCEI provides data products from the Hydrographic Survey Meta Data Base (HSMDB) in BAG format.[5]


The navigation surface concept requires to estimate not only the depth but also the uncertainty associated with it.[6] Furthermore, to support safety of navigation applications, a means to over-ride automatically estimated depth with 'Hydrographer Privilege', that is to specify directly the depth determined by an analyst. Finally, the format metadata provide a way to describe the data, from collection to processing methods, from geospatial extents to the responsible party. The Open Navigation Surface (ONS) project implemented the format to incorporate all of these requirements as well as be portable, platform neutral, vendor-neutral.

The project started with the creation of mailing lists. After a Call for Participation, a first meeting was hosted by the Center for Coastal & Ocean Mapping on 21–23 January 2004. Participants from CARIS, CCOM/JHC, IVS, NOAA, NAVO, SAIC, and SevenCs attended this first meeting. The outcome was the definition of the requirements and structure for the format.[2]

The following meeting was held on 18–22 July 2005 resulting in an alpha building of the library. The use of the library was then demonstrated at Shallow Survey 2005 conference using a number of processing applications (i.e., IVS Fledermaus, CARIS HIPS, and SAIC SABER).[2][7]

The first stable version (v.1.0.0) of the library was released on 8 Aprile 2006.[8]

In April 2012, the IHO S-102 Bathymetric Surface Product Specification become the first S-100-based standard to be officially adopted.[9] The standard is based on the BAG format (version 1.4).[10]

With release 1.6, the optional support for variable resolution digital elevation model was introduced.


Officially supported APIs[edit]

See also[edit]


  1. ^ "BAG v.2.0.1 Release Notes". Retrieved 25 Oct 2023.
  2. ^ a b c "Open Navigation Surface - Background". Open Navigation Surface. Retrieved 16 June 2018.
  3. ^ "The Open Navigation Surface Project". US Hydro 2005 Conference. 30 May 2005. Retrieved 16 June 2018.
  4. ^ "BAG --- Bathymetry Attributed Grid". Retrieved 16 June 2018.
  5. ^ "NOS Hydrographic Survey Data". NOAA NCEI.
  6. ^ Smith, Shepard (2003). The navigation surface: A multipurpose bathymetric database. Durham, NH: University of New Hampshire.
  7. ^ "The Open Navigation Surface Project: A Grid File Format for Hydrography" (PDF). Shallow Survey 2005 Conference. Retrieved 16 June 2018.
  8. ^ ONSWG (2 May 2018). Format Specification Document - Description of Bathymetric Attributed Grid Object (BAG) (1.6.3 ed.). p. 50.
  9. ^ Journault, Marc; Maltais, Louis; Kuwalek, Ed. "The New IHO S-102 Standard". Hydro International. Retrieved 18 June 2018.
  10. ^ S-100 Bathymetric Surface Product Specification (PDF) (1.0.0 ed.). IHO. Retrieved 18 June 2018.

External links[edit]