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Sparse band accorss Ireland?  XML
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barryhunter


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Joined: 13/09/2006 21:25:40
Messages: 27
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Plotting the Geonames database for Ireland in Google Earth, I notice there is a band across the country which seems to be less dense than the rest of the country.

I've also plotted the GNS database directly so it doesnt appear to be a geonames.org problem, unless of course its something I done. (unlikly as I just load data infile to a mysql table, and a really simple php script splits out kml)

Anyway does anyone know the reason, or have any ideas?

I've uploaded a screenshot here, I also tried zooming in to see if it just a rendering anomaly, see second shot. (notice also how the positions are more grided in the sparse area!)


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marc



Joined: 08/12/2005 07:39:47
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Hi Barry

This is a very interesting observation. Do you know whether this band is a politically problematic area? Perhaps a borderline between two conflicting parties? If yes then it could be a kind of censoring by nga.

Regards

Marc

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barryhunter


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Joined: 13/09/2006 21:25:40
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I don't think so as it seems to have very straight edges, there is conflict between the Republic of Ireland and Northern Ireland (currently part of UK), but this band certainly doesnt align with any county/country boundaries.

Somehow I can only guess it a technical limitation of how the data is processed to make the GNS dumps, as can't beleive this wouldnt be noticed.

In fact have just created a kml polygon that matches with it, screenshot, and download.
- see it doesnt seem to align with any boundaries, but does align with the Lat/Long grid quite well (bare in mind this polygon not very accurate, it hard to spot the actual border once get in close enough to plot!)

Also I've uploaded the KMZ file I used here (~330kb), incase it's of use. (btw I guess this is under a CC licence!)

Thanks

(as an aside, is there a reason to have underlining turned off on links? personally find it very hard to spot links in this forum!)

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marc



Joined: 08/12/2005 07:39:47
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Hi Barry

I have forwarded your question to the NGA (the National Geospatial-Intelligence Agency) as source of this data set.
Here the answer :

... I worked on the effort to take the names from Irish mapping and get them into the names database in the late 90s. I left before the project was done and assumed that all the sheets had been finished. However your note plus a check on the maps in the office convinces me that three sheets have not been completed. This explains the pattern of names density in the graphic. The more irregular pattern in the west is due to sheet overlap. I can not vouch for when this might get completed, but at least knowing about it is useful.
 


Regards

Marc

PS : Underlines have been turned on. There was no particular reason for not having them turned on. It was just the default behaviour of the forum software running this forum.

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barryhunter


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Joined: 13/09/2006 21:25:40
Messages: 27
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Thanks for checking, at least we know there is a 'reason', also interesting to learn that these datafiles are compiled from paper maps!

Also thank you for the underlines

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