OS MasterMap Topography Layer Overview

This overview introduces OS MasterMap Topography Layer and gives context for all users – highlighting key features, providing examples of uses, and listing details such as file sizes, formats, etc.

OS MasterMap Topography Layer contains features that represent objects in the physical environment, such as buildings, fields, fences, and letter boxes. It also includes intangible objects, such as county boundaries and the lines of mean high or low waters. There are over 500 million features in the product. Coverage includes the whole of Great Britain (i.e. England, Scotland, and Wales).

OS MasterMap Topography Layer in 'Outdoor Style'.

Product highlights

The key characteristics and benefits of OS MasterMap Topography Layer are:

• Individual real-world topographic features are represented by points, lines, and polygons, each with their own unique reference, called a topographic identifier (TOID).

• Each uniquely referenced feature has attribution that provides information about the real-world object it represents and metadata that tracks changes to the feature’s lifecycle.

• It employs a scale of data capture appropriate to the density of features – the higher the number of features within an area, the larger the scale used to survey them – ensuring the detail of individual features can be shown and with coordinates delivered in British National Grid (with the exception of vector tiles format, which is supplied in Web Mercator projection – EPSG:3857).

• The data is developed, managed and maintained by Ordnance Survey within one of the world’s largest spatial databases.

• The data is delivered as a seamless, geographically contiguous area for the whole of Great Britain.

These characteristics mean that a user may use the product in a wide variety of ways, including:

• Improving the accuracy of their own derived data.

• Improving their data capture processes.

• Creating consistency and achieving maintainable standards within geographic data holdings.

• Establishing a common reference between their own datasets and data they may wish to share with other organisations.

• Improving the visual clarity of data and aiding the visual interpretation of data.

• Using OS products in an integrated manner to derive additional information. For example, appending OS AddressBase data to OS MasterMap Topography Layer buildings data to derive building names and addresses.

• Identifying and managing change in their area of interest (AOI).

• Creating historical views of their AOI.

• Enhancing the queries that can be run on their data, thereby providing better information for decision making.

Index

This overview document provides a high-level introduction to OS MasterMap Topography layer and covers the following topics:

• Product Purpose

• Product applications

• Product details

• Styling

• Product themes

• Coordinate reference systems

• Product supply

• Change management and data association