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

Donal Diamond donal.diamond at gmail.com
Thu Mar 26 22:53:43 UTC 2015


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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