OS MasterMap Topography Layer

OS MasterMap Topography Layer | Data Products | OSOrdnance Survey

OS MasterMap Topography Layer is the most detailed and accurate view of Great Britain's landscape. It includes features representing the manmade and natural environment, including: land cover, buildings, water, rail, height, heritage, structures, administrative boundaries, and roads, tracks and paths.

This product is updated every six weeks

A representation of OS MasterMap Topography Layer data

The OS MasterMap Topography layer is presented seamlessly with more than 500 Million real world objects – all uniquely identified – including roads, buildings, parks and waterways. All data is managed and maintained by Ordnance Survey within one of the world’s largest spatial databases.​

Features

Mapping from the ground up

OS MasterMap Topography Layer gives you the confidence to make location-based decisions about assets, services, environmental risks, customers and operations.

Accurate referencing

All features are assigned a unique Topographic Identifier (TOID) to allow assets to be geo-tagged. This makes it ideal for monitoring assets such as pipelines, pylons, bridges and warehouses.

Enhanced features

OS MasterMap Topography Layer includes enhanced features such as Building Height Attribute, enabling users to analyse the built environment, and Sites Layer showing the main points of access to key sites.

The foundation of the OS MasterMap family

With OS MasterMap Topography Layer, each feature is a record in a database. Each of these records has information about the feature’s position and shape on Earth – its geometry – as well as details about it termed ‘attributes’. It provides an accurate visual context to help you interpret addresses, routes and imagery provided by the other layers.

Use cases

The user may use the Topography Layer in a wide variety of ways, including:

• Improving a user’s data capture processes and the accuracy of a user’s own derived data.

• Aiding the visual clarity of data and the visual interpretation of data.

• Achieving consistency and maintainable standards within geographic data holdings.

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

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

• Using the products in an integrated manner to derive additional information.

• Identifying and managing change in their area of interest.

• Creating historical views of their area of interest.

A common use for the product is by organisations who have their own GI and wish to examine it in relation to the real world around them. An example would be utility companies that have assets both at surface and below surface level. They frequently need to visit these assets, either for repair, maintenance or to add new assets. By viewing their infrastructure against the features in OS MasterMap Topography Layer, it will help their crews locate the assets, become familiar with the area before they leave their depot and allow them to provide a better user service by identifying those nearby premises that need to be notified about the works.

Summary

• Access: Download

• Data theme: Buildings, Land, Land Use, Structures, Transport, Water, Administrative and Statistical Units

• Data structure: Vector – Identifiers

• Coverage: Great Britain

• Scale: 1:1 250 to 1:10 000

• Format: GML 2.1.2, GeoPackage, Vector Tiles

• Ordering area: All of Great Britain or customisable area (5 km² tiles or user-defined polygon)

• OS Data Hub plan: Premium Plan, Public Sector Plan

Additional information

The need for a national topographic dataset

OS MasterMap Topography Layer was developed in response to the need for a national topographic dataset that offers users a more sophisticated type of data that represented the world in a more realistic way and was more aligned to the increasing use and functionality of GIS and spatial technology with organisations.

The advantages of TOIDs as a referencing system

Every feature within OS MasterMap has a TOID (TOpographic IDentifier) as the unique reference. This makes it possible to identify any single feature within the dataset with no ambiguity.

Alternative referencing systems can be subject to interpretation between organisations and users, leading to challenges in accurately matching data when exchanging information with others. TOIDs provide a persistent reference throughout a features lifecycle; even if a feature undergoes change the TOID remains the same. This allows customers to link their own data and track change over time.

Having unique references is essential to making the most out of storing data within a national data repository, as these rely on unique referencing to be able to store, sort, manage, query and retrieve data efficiently.

Types of real-world objects represented in the Topography Layer

Please see our real-world object catalogue (PDF). It lists every type of real-world object in the OS MasterMap Topography Layer specification, and details how it is represented by Topography Layer features.

Accuracy of OS Mastermap Topography Layer

We define accuracy in three ways:

• Absolute accuracy – how closely the coordinates of a point in the dataset agree with the coordinates of the same point on the ground (in the British National Grid reference system).

• Relative accuracy – positional consistency of a data point or feature in relation to other local data points or features within the same or another reference dataset.

• Geometric fidelity – the ‘trueness’ of features to the shapes and alignments of the objects they represent when testing the data according to the dataset specification against the ‘real world’ or reference dataset.

Available scales for OS MasterMap Topography Layer data

For cartographic representation, OS MasterMap Topography Layer is captured and designed for display at 1:1 250, 1:2 500 and 1:10 000 scales in urban, rural and mountain/moorland areas respectively.

In GIS OS MasterMap can be viewed over a considerable range of scales. The most scale-sensitive feature types, such as cartographic text and symbol features, are fixed in size and rapidly become less clear at smaller display scales (that is, when zoomed out).

OS MasterMap Topography Layer is also suitable for use in non–cartographic applications where the concept of scale is less applicable.

OS MasterMap revision policy

Read information about our policy for updating large-scale data, directly affecting OS MasterMap Topography Layer. Learn how we prioritise revision activity, and view the currency, definition, and criteria of categories of change.

View the OS MasterMap revision policy

Guides

You can find additional information and documentation about the OS MasterMap Topography Layer product on the 'OS MasterMap Topography Layer Product Support page' on the OS website.

We recommend you read the following guides:

• Getting Started with GeoPackage

• Getting Started with Vector Tiles

Additional information and guidance about geographic information systems (GIS) is available on the 'Geographic Information Systems page' of the OS website.

How to get this product

Access to this product is free for PSGA members. Find out if you are a PSGA member or try out a sample of OS MasterMap Topography Layer data by visiting the Topography layer product page here with links to all of the relevant resources. Alternatively, you can try out the full product by applying for a Data Exploration license here.