24
Apr
2017
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The making of OS VectorMap District

The saying goes that it takes a village to raise a child, and it’s certainly a cross-team effort to create and maintain an OS OpenData product within OS. So, in addition to our surveying teams capturing changes across Britain and adding them to the 500 million features in our geospatial database, we caught up with some of the people who work on OS VectorMap District, our customisable backdrop map.

Raster version of OS VectorMap District

Creating and releasing OS VectorMap District

A couple of months ahead of a new release of OS VectorMap District, Derek Howland and our ‘GenIE’ team extract the data from our core database. We use this core large-scale data to derive OS VectorMap District so that OS OpenData customers can benefit from our meticulous revision policy and enjoy access to open data which is consistent and up-to-date across the whole of Great Britain. The sheer volume of this data means we process it in ‘partitions’ (created using the national road network) and then ‘stitch’ the data back together.

After processing, the data is stored and validated, to ensure consistency of content and currency. Edits which are identified by the system are manual edited in the Cartography team using their wide range of skills and knowledge to resolve any critical non-conformances in the content store data. This is fairly minimal – affecting about 650 features out of 24.5 million features in the content store!

We can then apply generalisation and validation against the OS VectorMap District product specification. The system then automatically creates national coverage products in multiple formats (vector and raster) and packages them ready for customer supply.

Before we’re happy to release the data to the world, Graham Sanson and his Product Assurance team step up to ensure we are as accurate and consistent as possible in OS VectorMap District and all OS products. We check that the data matches the product specification and any industry standards for the data type (for example, being INSPIRE-compliant for OS Open Names, or OS Open Map – Local).

The team are also looking for other errors that affect our customers’ use of the data – if a text string has double spaces, spelling errors or ‘invalid’ characters in it, for example, an emergency service may not be able to load or query a location in their command and control system.

Managing OS VectorMap District and helping people use it

Producing the product is just one stage of the journey. We still have a lot of work to do to ensure it’s as user-friendly as possible.

Chris Wesson is in our GeoDataViz team, and works hard to ensure that our data users benefit from the same cartographic quality that is synonymous with our more traditional paper and raster map products. For OS VectorMap District, we work alongside our developers, considering visual needs and principles when creating and generalizing a new or improved product. We provide cartographic stylesheets, with a guide, to make our data easy to use and understand. Some of our customers prefer to consume raster image files. These are made by styling our internal database in a GIS and form the basis of the customer-facing stylesheets. For our open mapping, we currently have two styles – full-colour and backdrop. Full-colour is easy to view on most devices and facilitates a simple overlay; backdrop is a contextual base map to be used beneath further datasets.

To create the data stylesheets, we load the product data before its release. We use the data’s attribution to assign different colours and strokes to different features and to create labels. These expressions are viewable and editable by our customers. We also take the time to create patterns and symbols. All of this is very time consuming but we do it once so that our many customers don’t each have to bear this cost. Internally, we keep our core colour values for each style in a spreadsheet for easy reference. Externally, we share the product stylesheets on GitHub for easy access and versioning. We also run workshops for those who wish to delve further.

Our Product Management team, including Jonathan Field, work to ensure that it is as straightforward as possible for individuals, developers, community groups, social entrepreneurs, commercial businesses and government organisations to harness the power of our open datasets.

As well as the stylesheets created by the GeoDataViz team, we create product guides with all the technical information needed to make use of the product including the scales it should be viewed at, possible use cases, and the data structure of the product.

Our getting started guides help newcomers to the world of geographic information to download the data from our OS OpenData portal and then import data into various GIS packages, including the open source QGIS.

As you would expect, these resources can’t answer every question, and sometime users need a helping hand. This is where Charlie Adams and our Customer Service Centre step in. We’re on hand to answer your OS OpenData enquiries, Monday to Friday from 8.30am to 5.30pm. You can contact us in a way that suits you: email, phone, Facebook, Twitter, the Contact Us form on our website (or even send us a letter). Whether your query is complex or a simple “how do I?”, we’re happy to help you as best we can. If our highly knowledgeable advisors don’t know the answer straight away, they’ll make sure they find someone in OS who does and get back to you.

And of course, there are many more teams who work behind the scenes and have a hand in OS VectorMap District too, but this gives you a flavour for how we strive to not only produce products that are consistent, up-to-date and accurate, but also work hard to make sure they’re used as widely as possible. If you’d like to try out any of our OS OpenData products, just visit our website. And any questions, just let us know.

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