There are two different approaches used in mapping mangrove areas in OSM
1) Treat the boundary of the mangrove and the openwater sea as the coastline, and then map the area between that line and the "dry" land as wetland. This means that the wetland symbols are rendered over the white colour of the land, and that at zoom levels 12 and lower the mangrove areas simply get shown as white, with the sea outside them.
2) Treat the boundary of the mangrove and the "dry" land as the coastline, and then map the area between that line and the openwater sea as wetland. This means that the wetland symbols are rendered over the blue colour of the sea, and that at zoom levels 12 and lower the mangrove areas simply get shown as blue sea.
Early today I added some mangrove areas and followed approach 2 because the coastline had been accurately mapped along the mangrove / dry land boundary, as so I simply added the mangrove area outside this, as it seemed the existing mapper had cleary thought the coastline should be at the dry land boundary.
However at http://www.openstreetmap.org/#map=14/9.7497/125.6105 both these approaches have been used. Approach 1 has been used for Lamagon Island, where the boundary of the mangrove area and the sea is tagged as coastline. But Approach 2 has been used for the island immeditately south, where the boundary of the dry land is tagged as coastline.
On further investigation I see at http://www.openstreetmap.org/#map=14/9.7003/125.6415 that Approach 1 has been used.
Has this issue been discussued before within the Philippine OSM community, with any recommended way of mapping mangrove areas being decided upon?
Regards David _______________________________________________ talk-ph mailing list talk-ph@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-ph
