The British Caving Association

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 Post subject: OS Grid Ref. Resolution
PostPosted: Fri 15 Sep 2006 15:48 
Site Admin

Joined: Thu 29 Dec 2005 23:22
Posts: 298
Location: Axbridge, Somerset, UK
Footleg wrote:
2) RE: The suggestion to limit location information to 1km resolution: I think this is the wrong approach. Internally the database has to store location information to at least 10m resolution in order to record where a site is. However this field should have restricted access and a second field be used to store the published location. This second field can be expressed to an appropriate resolution for the site. Publicly known caves can be given to 10m (OS grid ref. format like AA 0000 0000). Sensitive locations can be expressed to 1km resolution.

I suggest 10m resolution as this tends to eliminate variations in typical GPS readings for the same site, and helps to distinguish between duplicate entries and closely located sites.

Hmm, I should have put 'optionally' in the relevent sentence.

It was always intended to internally store the NGR to whatever resolution it was provided. That should include 1m resolution if that is what the data-provider felt was sensible, but might only be to 1km resolution or worse if the data-provider felt uncomfortable.

When it comes to publishing either to the web or paper or whatever I was suggesting that the data-provider could specify the resolution at that stage. So internally it might be to 10m but as published on the web it would be to 1Km resolution.

There is a political issue here which I don't want to get embroiled in. I do not want to be the person deciding the resolution of the NGR or if it is displayed at all. By giving the data-provider the facility to control this, I hope to leave them with the responsibility.

I can see a situation where I might have to reduce the resolution or remove the NGR at the request of the landowner or Regional Council. I would never increase the resolution. Hopefully this won't happen, which shouldn't if the data-providers are responsible.

Dave Cooke
BCA Webmaster, BCA Web Services, National Cave Registry Co-ordinator, CSCC Treasurer

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