OpenStreetMap

Polygonizing Philippine islands

Posted by maning on 13 February 2014 in English (English)

Recently, I've been trying to move tags on island nodes to its way (natural=coastline) following the best practice of One feature, one OSM element. The original place=island nodes were from an GNS import. Most of these islands now have a digitized coastline so it makes sense to add the place=island and all its tags to the ways.

To do this, I ran an overpass query to get all place=island nodes within a given boundingbox. Code is below:

<osm-script output="xml" timeout="25"><!-- fixed by auto repair -->
  <union>
    <!-- query part for: “place=island” -->
<query type="node">
  <has-kv k="place" v="island"/>
  <bbox-query s="4.061535597066106" w="111.57714843749999" n="21.166483858206583" e="127.11181640625"/>
</query>
</union>
<!-- print results -->
<print mode="meta"/><!-- fixed by auto repair -->
<recurse type="down"/>
<print mode="meta" order="quadtile"/><!-- fixed by auto repair -->
</osm-script>

The result will show on the map like this:

Overpass query island nodes

Then, I clicked the "Export" link to download the data into JOSM.

Slowly, working my way on each island node, I transferred the tags to the coastlines. If there is no natural=coastline, I trace them using Bing's high-res imagery and then add the tags in the island nodes.

Right now, I'm focusing my efforts on smaller islands where the natural=coastline is on a closed way. I will start working on the islands relations once I finish the closed ways. Might take a while though (current count is ~2,500 nodes).

Location: Bitaogan Barangay Road, Libtog, Iloilo, Western Visayas, Philippines

Comment from 4rch on 13 February 2014 at 13:48

Good work!

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