Creating a topographic map from OS NGD Data
A Lightning Talk
Which OS NGD layers are needed for a topographic map?
A number of the layers from different Themes are required to create a seamless coverage of polygons. Other features represented by lines and points are also required.
The layers needed come from:
Water Features
Water Network
Transport Features (Road and Rail)
Building Features
Land Features
Structure Features
Can the data be styled to look like a topographic map?
It is possible to style OS NGD data to look like a topographic map and a set of styles has been created to enable users to style the polygon layers in this way (lower image).
Official styles for the linear and point features have not been published with the first release of OS NGD data, but may be published at a later date based on customer feedback.
The two styles are for a default style coloured differently per theme (upper image), the other is for a basic topographic style (lower image).
Where can users find the style files?
Ordnance Survey have created a set of style files in 2 stylings which can be accessed on GitHub
https://github.com/OrdnanceSurvey/osngd-resources
The styles have been created in the following formats:
ESRI LYR files
QGIS QML files
Geoserver SLD files
Are there any styling considerations for users?
There are a few things that need to be considered if attempting to create a topographic map from OS NGD data:
OS NGD data has been created primarily for analysis not for cartography
A number of layers need to be brought together and styled specifically in order to recreate a topographic map. For example Water Features Water and Water Network Waterlink are both required to create a cartographic water layer as the features give you the polygons and the network is needed for the lines where the river is too narrow for a polygon.
There is no cartographic text in OS NGD data. To create text on the map requires labelling linear features (road and river names from transport and water network) or point features (structure points). Building names and numbers need to be labelled from either addresses or residential sites polygons
Is it possible to style OS NGD data like OS MasterMap Topography Layer?
It is possible, but it is not straight forward because of the factors already mentioned:
OS NGD data has been created primarily for analysis
There is no cartographic text
Development is underway to create styling that looks similar to OS MasterMap Topography Layer. However, this is quite complex with up to 200 different categories needing to be styled for some of the layers.
For example there are:
200 classifications in Structure Features
102 classifications in Land with some specific vegetation styling
23 classifications in Transport Features - Road Tracks and Paths
Links that may be useful:
This content has been developed from what was originally a Lightning Talk PowerPoint slide set. These slides are available to PSGA members to view and download from the PSGA members area of the OS website
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