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I emailed the Geography team at the ONS: > Hi geography team, > > I work on GOV.UK Notify, which is a service run by Government Digital Service (part of the Cabinet Office). I was given your email address by [redacted] who’s been helping answer some of my questions on the cross-government Slack. > > We’re using some of the boundary datasets from the Open Geography Portal, and mostly they’ve been excellent. > > In the abstract, the problem we’re trying to solve is, given a point outside an area, what is the minimum distance to a point within that area. So, for example, if a crow was somewhere in Cardiff, what’s the shortest distance it would have to fly to reach somewhere in the Bristol local authority district? > > We’ve noticed some problems with the data that means our calculations would be wrong. We’ve noticed this around Torquay, Norwich and Bristol. Here are some screenshots of Bristol, from the generalised and full resolution boundaries: > > The artefacts I’ve highlighted are closer to Cardiff than any actual part of the land area of Bristol. They are either: > - in the sea > - land that’s part of North Somerset > > I suspect that this is being caused by the process of clipping the actual region of Bristol (which, unusually, extends into the water) to the mean high water line. > > I’ve worked around this by filtering out any polygons that are smaller than ~7,500m². It’s a bit hacky because parts of the Scilly Isles start disappearing. That’s not a problem for what I’m working on, but it would be nice to not need the hack. > > So my questions would be: > > - Is there a better way to remove these artefacts than filtering by area? > - Is there a plan to remove these artefacts from the data in future releases? > > Thanks in advance, > Chris They emailed back to say: > Hi Chris > > Thank you for your enquiry. > > We have completed the amendments to the LAD MAY 2020 BFC and BGC boundaries as mentioned so you should be able to download them from the portal now. > > Hope this helps. > > Kind regards > [redacted] This commit brings in the files they’ve updated. We still have to do some filtering (but now at a higher resolution) because they haven’t fixed Norwich yet. I’ll email them separately about that.