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I stumbled upon an island not rendering properly. I have made several attempts to correct this by trying something a little different with the island (Abbey Island) that don't seem to appear on the map. If anyone could take a look and let me know what is wrong it surely would be appreciated.

asked 16 Aug '21, 20:53

yasobara's gravatar image

accept rate: 0%


The missing coastline key might have well been the culprit here. But note that changes in the coastline are not immediately reflected in the rendering on You can read up on the topic in our [wiki] to understand how coastlines are rendered.

Please wait a few days to see if your changes made a difference.

(16 Aug '21, 22:08) TZorn

The island and the beach are visible now.

(19 Aug '21, 20:45) TZorn

I used your co-ords to get this. I seems to me that the coastline was partly created clock wise and part anti clock. I have only mapped a few lakes with islands and can't remember which side of the line land is supposed to be on but it is in the wiki. I have looked it up and..

The coastline should be created anti-clockwise with the land to the left as you create a coastline. With P3 and JOSM editors the way direction can be reversed. When I looked at your island the greater part of the coastline needed reversing so the land was to the left. You could look at another location and inspect the tagging see the JPEG note the arrow in the tool box indicates the "way" direction.

alt text

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answered 16 Aug '21, 23:36

andy%20mackey's gravatar image

andy mackey
accept rate: 4%

edited 16 Aug '21, 23:45

Looking at the history I understand Yasobara first added the coastline key alltogether and then with the next change set corrected the direction. But as I wrote in my comment above it takes a while for the altered coastline to be rendered.

(16 Aug '21, 23:59) TZorn

This should be a comment but i wanted to illustrate the issue. I do not think it will render for the reasons in my first answer ( land should be to the left of the coastline "way" ) but a further check shows this when I select one section of the coastline it also selects some rocks that are in a multi polygon, I do not think this is correct either. alt text

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answered 17 Aug '21, 08:55

andy%20mackey's gravatar image

andy mackey
accept rate: 4%

Andy, I don't see the issue for Abbey Island. It is made up of two ways: 544850833 and 544852438. Both run counter-clockwise and have the land on the left.

I guess you are referring to Ruby Beach. Those rocks you see on your screenshot belong to that multi-polygon. I find it strange the beach is mapped outside the coastline alltogether but then again I'm no expert in beach mapping. The coast-line should reflect the mean high water level, so I guess a beach could extend further out.

(17 Aug '21, 09:16) TZorn

Using Potlatch editor I am seeing 544850833 as clockwise. I would have thought it would be easier to have been mapped the island as a single way. The island was mapped a a single way, before the questioner edited it, I think. I do realise many coastlines are very large and need to be joined sections.

(17 Aug '21, 10:13) andy mackey

I don't see any arrows in your screenshot. Are you using the latest data? The direction was reversed in changeset 109719198

(17 Aug '21, 10:18) TZorn

Thanks TZorn cntl F5 updated the data that had been cached and both sections are anticlockwise. Let wait and see here it fixes the issue. Happy Mapping:-)

(17 Aug '21, 10:38) andy mackey

For info: Potlatch shows the direction of a way with the arrow in the Toolbox ( usually bottom right) and allows reversal ( by clicking on the arrow) of a way if it has been plotted in the wrong direction, for example a one-way street or a lake.

(17 Aug '21, 10:42) andy mackey

This bit shows is in the opposite direction according to the arrows. or have I selected something other than the coastline? alt text

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answered 17 Aug '21, 10:02

andy%20mackey's gravatar image

andy mackey
accept rate: 4%

Please excuse me if I'm completely wrong. It seems to me that Abbey Island is not mapped as an island because it is not completely surrounded by water. The Way: 544852438 (part of Abbey Island multipolygon) is not a water feature. If this is the problem I don't know what the best amendment/correction would be, possibly trial and error of various methods. Maybe make the beach area tidal water, make the island a single polygon with a continuous coastline.

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answered 20 Aug '21, 09:48

BCNorwich's gravatar image

accept rate: 20%

It appears to only be an Island at a high tide. which would explain why the mainland side coastline had been mapped in correct direction for the mainlands coast, but not for an island. I am not sure if an island that is connected for a greater part of the day is an island even though many are called islands around the world.

(20 Aug '21, 12:33) andy mackey

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question asked: 16 Aug '21, 20:53

question was seen: 934 times

last updated: 20 Aug '21, 12:33

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum