Open Navigation Surface

Esperanto for Hydrographers!










(2022-12-15) Source packages for version 2.0.1 of the Open Navigation Surface library are now available. (read more)

(2020-02-25) Minutes of the nineteenth ONSWG meeting. (read more)

(2019-10-16) Minutes of the eighteenth ONSWG meeting. (read more)

(2019-05-17) Meeting notes from the development meeting at US Hydro 2019 are now available. (read more)

(2018-11-23) Meeting notes from the development meeting at Shallow Survey 2018 are now available. (read more)

(2018-05-02) Source packages for version 1.6.3 of the Open Navigation Surface library are now available. (read more)


The Navigation Surface paradigm is a design for a databased alternative to traditional methods of representing bathymetric data. It aims to preserve the highest level of detail in every bathymetric dataset and provide methods for their combination and manipulation to generate multiple products for both hydrographic and non-hydrographic purposes. The advantages of the method over traditional schemes are such that a number of commercial vendors have adopted the technology. However, this means that there is a strong requirement for a method to communicate results in a vendor neutral technology. The Open Navigation Surface (ONS) project was designed to fill this gap by implementing a freely available source-code library to read and write all of the information required for a Navigation Surface.

The Navigation Surface concept requires that in addition to estimation of depth, we must also estimate the uncertainty associated with the depth. In order to make the system suitable to support Safety of Navigation applications, we also require a means to over-ride any automatically constructed depth estimates with ‘Hydrographer Privilege’, essentially a means to specify directly the depth determined by a human observer as being the most significant in the area (irrespective of any statistical evidence to the contrary). Finally, we must provide data on the data, or metadata, which describes all aspects of the data’s life from methods of capture to processing methods, geospatial extents to responsible party. The ONS project provides means to incorporate all of these requirements in a portable, platform neutral, vendor neutral format.

The ONS project has as its primary goal to foster and support the development of a source level library to read and write the Bathymetric Attributed Grid (BAG) data format. This web-site is intended to provide current information on the project, news, status, and downloads of the source base.

Documentation for the current stable release of the BAG data format and C++ and Python APIs (and how-to guide for using these APIs) can be found here.