
The US National Geodetic Survey (NGS) and the Canadian Geodetic Survey (CGS) have finalised an agreement to use a common grid format, the Gridded Geodetic data eXchange Format (GGXF).
The new format is expected to enable the two countries to more easily exchange and share data on positioning and navigation as the US moves towards modernising its coordinate system, the National Spatial Reference System, in 2025.
The GGXF will become the official format for all products and services released with the modernised National Spatial Reference System. NGS has already begun back-translating older grids into the new format.
According to the UN-GGIM, the use of a single, standard, grid file format such as the GGXF offers several advantages:
- Grid producers do not need to create file formats themselves, nor provide their own software to read and interpolate their gridded data, nor concern themselves with lack of take-up of their data due to its proprietary distribution format;
- Geospatial software developers need to read only one grid file format, eliminating the need to repeatedly revise their software to import different grids;
- Users can use a new grid file as soon as it becomes available, without having to wait for their application vendor to produce a software upgrade.
The UN-GGIM says the GGXF is “intended to accommodate any gridded geodetic data, in particular grids supporting geoid models, coordinate transformations, velocities and deformations” and “has been designed to support multiple levels of data resolution, computational efficiency, and be straightforward for grid producers and developers to use”.
In other news, NGS, the US Center for Operational Oceanographic Products and Services (CO-OPS) and US Office of Coast Survey (OCS) staff have joined with US National Weather Service and US Geological Survey (USGS) personnel to launch a new Datums Working Group.
The USGS, which maintains a network of streamgages and water level stations, also is preparing for the modernised National Spatial Reference System, and is adapting its workflows for the releases of the North American-Pacific Geopotential Datum of 2022 and the National Tidal Datum Epoch in the next few years.
The current epoch, established by CO-OPS, spans from 1981 to 2001. The new epoch will span from 2002 to 2022.