OS MasterMap^® Topography Layer - Latest news

Tidelines

We may recall some time ago we told you that we intended to remove tidelines from the Topography Layer. The process to remove these has now commenced. You will find that these features will begin to be removed from the next refresh of data that you receive and this is scheduled to have been completed by July 2010.

Removal of duplicate text over tile edges 

Within the OS MasterMap Topography Layer we have identified the removal of obsolete duplicate text as a valuable content improvement for our customers.

Why does the duplicate text exist?

The duplicate text which appears in the Topography Layer is as a result of the hard tile edges which were a feature of Land-Line^® data, the predecessor to the Topography Layer. In Land-Line if a named object, house, tank, building etc. appeared in more than one tile the cartographic text would appear on each tile. See example below:

Why do we need to delete this text?

Due to the way in which the OS MasterMap Topography Layer is delivered to our customers this text as it is now redundant. Should a customers area of interest include named objects which appear over tile edges the customer will be delivered the whole polygon. The consequence of this is that customers would receive multiple instances of cartographic text relating to the same feature.

When will these features be removed from the data?

The process of identifying the duplications is underway at the moment and should be completed by the end of March. Once this is completed the programme to delete the duplicate text will commence and will the deletions will form part of your next Change Only Update (COU) or from your next refresh and should be completed by June 2010.

How many duplicated will be removed?

It has been calculated that there are over 760,000 instances of duplicate text which will be removed from the data by the completion of this project.