[OSM-talk] Ireland coastline - final polish

Dermot McNally dermotm at gmail.com
Wed Jul 11 19:38:21 BST 2007


I've recently finished cleaning up the Irish coastline as imported
using Almien Coastlines. The lowzoom tiles seem by now to have caught
up with the most recent highzoom ones, leaving behind only a few
artefacts. These can only be as a result of one of three things, none
of which I can easily repair, so maybe some kind person could have a

The possible causes (in order of probability):

1. All-water tiles that the lookup table thinks are land. There are a
few of these, mostly around the irregular west coast (loads in Galway
Bay), but also one in Lough Foyle (on the north coast). I don't know
how to update the lookup table, but there aren't many to fix for
someone that does.

2. My own errors. For those areas still not rendering correctly (there
are water filled islands showing in Galway Bay and a little clockwise
of it at the mouth of Killary Harbour). I have looked to try and spot
any errors, but I can't find any.

3. Rendering bugs. I recall that when the current trick for telling
land from water was new, a number of unusual circumstances triggered
bugs that could only be fixed within the renderer. Maybe some remain.

The new coastline looks great, but it would be nice to get rid of the
few outstanding issues.


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