[talk-ph] Luzon Coastline

Jim Morgan jim at datalude.com
Fri Feb 20 08:20:43 GMT 2009


I've been trying to figure out the Luzon coastline around Zambales, as its driving me nuts. Personally I think it looks terribly offputting to see such a glaring error, especially as we're seeing some new members recently. 

So I looked at the coastline checker here, 
	http://tile.openstreetmap.nl/coastlines.html?zoom=9&lat=15.1027&lon=120.35419&layers=B00T

and, using the notes here
	http://wiki.openstreetmap.org/index.php/Coastline_error_checker

investigated a few of the Big Red Dots. 

>From looking at them in JOSM, the Big Red Dots seem to be at areas where the coastline is split into different sections. The sections have the same tags i.e.
 layer=-1
 name=Luzon
 natural=coastline
and the direction is correct -- wet on the right. 
But they have different description and Notes fields.

Is this the problem then? That the notes fields are different and that this has somehow made the renderer unable to recognise that they are the same coastline? I can't imagine that it is ... Or do the coastline segments need to be joined together? 

I understand that the islands outlined in red are only being flagged as wrong because they are currently "on land" so those will disappear when we get the coast corrected. 

Possibly related to this, I noticed that a section of the coastline had gone AWOL around Subic airport, and actually cut across the runway, so I put in a temporary section of coastline so that the coast goes outside the airport. Its very approximate at the moment, but at least it is topologically sound. 

Maybe I'll wait and see if this glitch was causing all the problems. I'm crossing my fingers that I haven't made things worse, but I thought I'd mention what I've been doing here, so that if the sea suddenly drains away from the entire Asian subcontinent, you'll know where to point the fingers of blame (and where to go to start fixing things ... .). 

If anyone else has any bright ideas on how to fix this coastline, please help me out here. I'm a little out of my depth (no pun intended), but its been broken for several weeks. 

Jim



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