Thanks for the comments! They help me to get the bigger picture, which
is not visible from just the tag names and definitions.
TL;DR summary: I think that for now we should render all the existing
tags with osm-carto, but make some of them appear earlier to encourage
smooth migration to a more precise scheme.
W dniu 01.12.2017 o 01:55, Martin Koppenhoefer pisze:
there is no problem with 2 different tags fitting for the same kind of
thing. These are also different in scope, leisure=nature_reserve is
for all kind of natural protected areas, while boundary=protected_area
is for all kind of protected areas.
My general findings are:
1. As I currently understand it, nature reserve is _always_ a type of
protected area, to begin with.
We were talking on osm-carto ticket with some people about private
reserves and even when someone told me "it's not about protection!" this
term was used immediately in the same sentence (or in the next one). =}
I guess they meant "it's voluntary and not formal", but still it's
intended as a protection of nature, so it's just a special, weak type of
protection.
2. The problem seems to be for a mapper to be more precise, since a
typical survey can reveal a sign with a name "XYZ nature reserve".
However this is not about just a name.
Boundaries are not visible on the ground easily, so a mapper who draw
them have to use some other sources and I believe there are more
informations available. Otherwise the area shape is probably not
verifiable, which would be bad anyway. And I think all of them are
areas, not the points (node would mean probably "here is the protection
area, but exact shape is not shown at the moment"), so boundary is also
a sure thing.
3. The name tag leisure=nature_reserve states that it's about leisure
(which of course might be for a given object), but it's always about
protection. So even if the value have merits, this key assumption is
wrong in general and misses more important property
(boundary=nature_reserve has only 35 uses).
4. Another problem is lack of coherent definition of protection other
than numbers and high-level classes.
The numbers seems to be derived from IUCN scheme (
https://en.wikipedia.org/wiki/IUCN_protected_area_categories ), but
wider: only categories 1-6 is IUCN-based and I don't know about the rest.
Especially class 7 is interesting for us: "*nature-feature area*:
similar to 4. but /without/ IUCN-level.", so i guess it's for all the
non-IUCN classified nature reserves. Probably most of the time this
should be clear from the boundary shape source.
It would be good to have more standardized subtags for common features:
- "nature" - protection_object=* is the same mess as numbers, when
talking about hierarchy levels, so maybe some subtag like
"nature_reserve=yes" would be useful
- "private" owner type (not the access type) -
governance_type=private_landowner would be great (if really used...)
- "voluntary" - but that might be clear from the lack of government or
international authorities influence
What about the solutions?
My suggestion for osm carto is to look at both tagging schemes for
nature reserves. I wouldn’t drop support for leisure =nature reserve
In summary, we have 3 popular but overlapping types now:
1. leisure=nature_reserve (77 264)
2. boundary=national_park (16 583)
3. boundary=protected_area (62 016)
Their general properties and relations:
1. has a wrong key, but nice value name, and is a subtype of 3.
2. has a nice value name and a proper key, it's also subtype of 3.
3. is very broad with precise, but not so common name, it also has
subtypes, which are useful for official classification, but are not
clear for all the other types of conservation
Therefore I would advice to:
1. Discourage leisure=nature_reserve and make it a subtag of
boundary=protected_area, like:
a) nature_reserve=yes - 2 uses
b) protected_area=nature_reserve - 22 uses
c) protected_area=nature - 61 uses
if needed, otherwise just use a protect_class=7 or other class if known.
2. Drop boundary=national_park, since it's easy to identify them all and
they are equivalent for boundary=protected_area + protect_class=2 anyway.
That's about cleaning the tagging. For rendering I would show all of
them as currently, just using different zoom levels, starting from z8
currently (this might change in the future, of course):
- z8+: national parks and wilderness areas (both are big by definition)
- z9+: important natural protected areas (class 1-6, with hatched 1a
probably)
- z10+: other natural protected areas (class 7, maybe also 12, 14 and 97-99)
- z11+: protected areas without class and leisure=nature_reserve
This is just a rough sketch, however it have some nice properties:
- all the existing schemes are visible (boundary=national_park can be
dropped later)
- more important objects are rendered first
- less precise tagging is rendered late
Another important factor might be their size (so for example small
national parks wouldn't be shown on z8), but it needs a lot of worldwide
testing.
--
"My method is uncertain/ It's a mess but it's working" [F. Apple]
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