Strange "overlapping water areas" test result

[naoliv]

Validate the attached example file and see that there is a warning about "overlapping water areas".
I can't see anything overlapping there.

[mdk]

simplified version (6 nodes, 2 ways)

[mdk]

I have striped down the example to 2 ways and 6 nodes.

Here are my findings without tracing the JOSM code:
1) There is not only a warning about "Overlapping Water Areas", but also two related other "Overlapping Areas" hints.
2) The "Overlapping Water Areas" has only to deal with natural=water. If you change it to natural=scree, only the two "Overlapping Areas" hints remain. Even if you remove all tags from the ways, the two hints appear (but you get two "Untagged ways" warnings as expected.)
3) If you imagine that the railway is a closed triangle (or you can really close it - it doesn't matter) than the water triangle is crossed by this missing railway segment.
4) If you move the water area inside or outside this railway triangle, the warning and the hints disappear.

So the overlapping area test has some general problems:
1) Normal ways (like the railway) are treated as areas, even if the are not closed and even if they have absolutely no tags!
2) Crossings of every kind of ways produce "Overlapping Areas" hints.

[mdk]

natural=wetland exaple with lots of warnings

[mdk]

I have also related problems with natural=wetland areas overlapping natural=water or natural=grassland etc.

On a lake, there are normally 4 different zones:

1. open water (natural=water)
2. waterside reed (natural=water & natural=wetland)
3. land side reed (natural=grassland & natural=wetland)
4. normal land (natural=grassland)

Is the attached wetland example a good mapping for this case? Than it should not create 2 warnings and 5 hints!

[mdk]

Btw: It would be helpful if the validator message for overlapping areas would contain both ways, not only one.

[simon04]

In 6630/josm:

see #9534 - "Overlapping areas" validator: do not generate warnings for non-closed/non-area-style objects

[simon04]

Replying to mdk:

Is the attached wetland example a good mapping for this case? Than it should not create 2 warnings and 5 hints!

Is this a common way of mapping those zones (I've never thought of such a case)? As long as this is an "official way", I'd prefer to stick to the warnings.

[anonymous]

Your question is, if this kind of mapping is "common"? For the area I'm mapping like ​http://www.openstreetmap.org/#map=19/47.37848/8.86184, ​http://www.openstreetmap.org/#map=17/47.39628/8.89572 or ​http://www.openstreetmap.org/#map=17/47.41359/8.90637, the answer is YES. For the rest of the world? I don't know.
In #9507 is an example with the comment ".. what is typical situation in many places".

Looking around I found some similar places:
​http://www.openstreetmap.org/#map=16/53.4386/8.3033, ​http://www.openstreetmap.org/#map=17/47.45138/7.92963, ​http://www.openstreetmap.org/#map=15/47.9915/11.0025, ​http://www.openstreetmap.org/#map=15/47.7616/10.3875, ​http://www.openstreetmap.org/#map=14/48.6292/15.2022, ​http://www.openstreetmap.org/#map=15/54.1411/11.8894
So here I stop, because the actual slow tile rendering sucks :-)

I hope this answer your question.

[simon04]

Thank you.

I'm unsure how to best handle this special case.

[anonymous]

There is a general problem with "transparent" areas like landuse=military, leisure=nature_reserve and natural=wetland. Is it mapping for the renderer, because renderer like Mappnik draw this areas "transparent" or is it the general nature of this areas so that they can (or should) overlay with other areas?

[mdk]

Does the fix of #10120 has any impact on this issue?

[skyper]

What is wrong with a lake, mayby, with intermittent inside a wetland? If you map it as MP and exclude the lake from the wetland it might be wrong as if the lake disappears over the season all could be wetland. This is a different situation compared to forest + lake.

I vote for ignoring natural=water inside natural=wetland.

[skyper]

Replying to mdk:

Does the fix of #10120 has any impact on this issue?

I am not sure but currently only the last example file (attachment:wetland_example.osm​) leads to warnings.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2024-02-05 12:56:34 +0100 (Mon, 05 Feb 2024)
Revision:18969
Build-Date:2024-02-06 02:30:58
URL:https://josm.openstreetmap.de/svn/trunk