[OSM-talk-ie] Irish boundaries map layer updates

Dave Foley dafo43 at outlook.ie
Fri Mar 27 20:17:57 UTC 2015

Great work Donal, that's really useful for checking mistakes with the boundaries.


> Date: Thu, 26 Mar 2015 22:53:43 +0000
> From: donal.diamond at gmail.com
> To: talk-ie at openstreetmap.org
> Subject: [OSM-talk-ie] Irish boundaries map layer updates
> The map layers showing Irish boundaries is now updated every 15 minutes.
> This includes county/barony/civil parish/ed and townlands.
> The map server starts updates at 05/20/35/50 minutes past the hour and
> should have all Irish edits up to 00/15/30/45 minutes past respectively.
> Updates should take about 2 minutes.
> I also updated the townland layer to show area in fractional acres from
> zoom 14 onwards. This may help you compare the acreage value shown on the
> GSGS3906 maps to help spot obvious errors.
> For example, I picked a spot at random below and you can see that there are
> a few areas that have the wrong acreage due to some townlands being missed:
> http://maps.openstreetmap.ie/oocmaps.html?zoom=15&lat=53.71215&lon=-6.91047&layers=000B0TFFFFTFFF
> eg Barfordstown is reported as 482 acres as we actually included  two
> townlands Barfordstown 283 acres and Boolies 198 acres. There's a similar
> issue with Calliaghstown nearby.
> When comparing fractional acres and  ARP (acres,roods, perches) on the map,
> bear in mind that:
> 1 acre = 4 roods
> 1 rood = 40 perches
> You'll also notice a small difference in the acreage size reported by
> townlands.ie and the map layer. That is due to the map layer transforming
> to Irish Grid when calculating the area to get a slightly more accurate
> calculation. Townlands.ie has to do a lot more analysis so uses a different
> spatial reference system.
> Anyway hope it helps.
> D
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