OS NGD Improvements
A high-level summary of data improvements implemented for the OS NGD.
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A high-level summary of data improvements implemented for the OS NGD.
Last updated
Was this helpful?
At Ordnance Survey, we are modernising our data creation platforms. This includes the creation of additional height data for our building and structures datasets. A recent key improvement we've made as part of these efforts was to improve the accuracy and granularity of the height evidence date attribute, which details the date of capture for the imagery used to derive the height data.
Previously, height metadata was derived from large imagery flight blocks (exceeding 500km²), which sometimes required several flights over multiple days. This occasionally resulted in buildings and structures being assigned an imagery date different from the actual capture date.
Our new system allows the population of imagery date metadata to a more granular level, using the appropriate flight block. This ensures there is only one imagery date per building or structure feature, giving a more accurate representation of height evidence date for a specific feature. As a result, from 10 May 2025, some customers using Change-Only Updates (COU) may notice that a small number of height evidence dates have changed to slightly older dates as we move to the new system. This change reflects more accurate data, not incorrect data.
This impacts some features in the following data schema versions:
Structures
Structure Feature Type v1.0
Structure Feature Type v2.0
Structure Feature Type v3.0
Buildings
Building Part Feature Type v1.0
Building Part Feature Type v2.0
Building Feature Type v4.0
Some customers may also see a larger than usual supply of COU if taking a daily supply of the above data schema versions as change begins to flow into the data from the start of our flying season, where data is captured using aerial imagery during the National Cyclic Revision (NCR) programme.
The .xlsx file below contains a complete list of features across all feature types that have a revised height evidence date that's earlier than previously stated.
Please see for more information about versioning in the OS NGD.