NOS - Externally Sourced Bathymetry Data

External Source Data

How to prepare data for nautical charting?
External Source Data (ESD), defined as data with potential value for nautical charting applications,
but was not acquired or contracted by Coast Survey for this specific purpose, is a critical input to
NOAA’s nautical charting mission. ESD is obtained from data archives, or in some cases, directly from
established ESD providers. If you wish to best prepare your hydrographic data as ESD for nautical chart
application, here are some guidelines to follow.
Most importantly, ensure you have included the required metadata to accompany your ESD,
otherwise it may have very limited, if any, value.
If it's not already licensed, select a data license to define any restrictions. Note that some of the
licenses will prohibit nautical chart application.
Adequacy of the data for charting is determined by the Category of Zone of Confidence in
Data (CATZOC), well-defined in the IHO S-67 publication, and summarized in this presentation,
“Publishing Data Quality.”
It is not a requirement, but in order to be charted as CATZOC A1, the data must meet IHO Order 1a
as defined in the IHO S-44 publication. Most critical questions to answer:
• Was there complete or partial coverage within the survey area?
• Were all features identified (or disproved) with a system capable of detecting and measuring
least depths?
• What is the positional accuracy of the soundings?
• What is the depth accuracy of the soundings?
Please submit any processed data, and final products (e.g. bathymetric grids and feature files), in
addition to raw data.
Questions? Please contact [email protected].
Thank you!

Office of Coast Survey

April 2022