OS NGD Improvements

A high-level summary of data improvements implemented for the OS NGD.

May 2025 – Height data enhancement for OS NGD Structures and OS NGD Buildings data

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 a small number of features in the following data schema versions:

• Structures

  • Structure v1.0

  • Structure v2.0

  • Structure v3.0

• Buildings

  • Building Part v1.0

  • Building Part v2.0

  • Building v4.0