[Tagging] State parks and state forests: specific tagging question, general mapping philosophy
kevin.b.kenny+osm at gmail.com
Tue Jul 26 19:11:14 UTC 2016
The immediate question: I have the boundary multipolygon for a large state
park. The park has several stretches of waterfront. In some places the
boundary of the park follows the high tide line. In others, it's set back
from the shore (and the waterfront may have another owner). And in other
cases the boundary extends far offshore (which may have implications for
boaters). How best to divide and tag it so that the park exists as a
unified entity, but does not result in rendering land or trees in the water?
Now from some gratuitous ranting, because I'm getting discouraged:
My last question here, regarding how to tag public lands for which
permission is required (but routinely granted) got answers that left me in
a deeper state of confusion. The general consensus seemed to be "there is
no difference between those and private lands other than the personality of
the landowner, and they therefore must be tagged alike: access=private".
That answer did not satisfy - I want a map that renders those cases
differently, and things tagged alike cannot be rendered differently."
Moreover, I don't hold out much hope that a formal proposal, wikified and
voted, would end any differently; the voters are mostly on this list.
(Also, nobody answered my question about how to initiate such a proposal.)
I'm leaving Long Island mistagged with "access=yes" and not touching the
"access=permit" on the New York City watershed parcels that I imported a
few months ago (without a peep on "imports" about that detail of the
So that particular aspect of the project is "on hold" for now.
I'm also trying hard not to resurrect the argument about "forests." The
general consensus is that there simply is no way to tag the case, important
in the US, of "a tract of land legally managed for wild-land resource
production (wood and other products)." In this community, that idea simply
cannot be separated from "land covered with trees". There are also other
confusing ideas such as a "natural wood". The last, it appears, means
either also "covered with trees" or else "virgin stands of old-growth
forest", and also appears to connote "unmanaged" - which is a
contradiction, since our few remaining tracts of wilderness are managed
intensively to keep them that way. I've come to accept that any correct
tagging will not render, and most nearly correct taggings will suffer from
rendering gaffes like trees in water. (The concept of "a pond in the
forest" apparently is sufficiently foreign that the phrase, on this forum,
is nonsensical to the point of being meaningless: "surely you mean a pond
SURROUNDED BY the forest?") So I do the best I can to tell as few lies as
possible while still choosing a tagging that will be visible on the
renderer, recalling that "boundary=protected_area" does not render. I don't
expect, given the amount of progress toward rendering it in the last two or
three years, that I'm going to see rendering of protected areas on any maps
I don't produce.
That's fine, I can live with doing my own rendering, although it
increasingly means that I have to keep my own data on the side because
there's no way to represent it semantically in OSM's tagging structure.
It's at worst an inconvenience.
STATE PARKS (and many other types of public land)
New York, like many US States, has a system of "State Parks," which are
land managed primarily for the purpose of public outdoor recreation. (Some
of them have secondary purposes such as resource conservation. In
particular, the large parks near the New York-New Jersey border exist at
least in part to protect watershed for the cities of New Jersey.)
Many, if not most of these parks, particularly the larger ones, are
multiple-use areas. They correspond roughly with "national park" in the
IUCN system - but I'm reluctant to use that terminology, since they are not
administered at the Federal level. "National Park" is a specific term in
the US, and it does not apply to State Parks. In any case,
"boundary=protected_area protect_class=2" seems made for them, and IUCN
appears to allow for the case where a government other than the national
one could designate such a thing. (On the other hand, on their site, they
accord New York's wilderness areas a protection class of VI - while they
enjoy virtually the strictest protection of any wilderness areas in the
country, and in my opinion are class Ib, and I tagged them thus.) So, I'll
accept that "state park" <=> "protected area". That doesn't help me with
rendering, of course. It'll just be a blank spot on the map.
So, what do to to make them show? "leisure=park" doesn't feel right. The
state parks I'm working on aren't small green spots in the city. Some have
large tracts of backcountry. A typical trekker will spend 2-3 nights in the
woods on a trip from Greenwood Lake to the Bear Mountain Bridge through the
parks. "landuse=forest" sort of works, except that every documented meaning
of that tag is a lie. The land is not managed to harvest forest products;
in fact, the taking of trees is forbidden. Nor is the land, in most places,
entirely covered by trees; the parks encompass lakes, marshes, scrublands,
and even developed sections.
But all right. I'll settle for either "landuse=forest" or
"leisure=nature_reserve" as something that at least does not misrender
horribly, and note that such tagging is retained for the benefit of legacy
PARKS AT THE SHORELINE
But now I trip over another issue. A fair number of state parks lie on the
shoreline, be it the ocean front, the Hudson River, one of the Great Lakes,
or any number of smaller waterways. In many cases, their legal boundaries
extend for quite some distance offshore. This is significant - it has
implications for boaters, for instance - and so we want to keep the
boundary (which militates for leisure=nature_reserve, which at least shows
If we were to tag landuse=forest or leisure=park or most such things, we
would run afoul of the fact that the current renderer will render such
areas as land or at least overprint patterns such as trees on them.
The argument could be advanced that the "human" perspective of the park is
that it consists of the land portions, plus some offshore regulated area
that's a different animal. And I suppose that I could therefore carefully
carve out water from the legal boundary, and create two different
multipolygons that share most of the ways, one to carry the "protected
area" designation and the other to carry the "landuse". That's starting to
get into some really detailed work for what I hoped would be an initial
sketch (but see below for some philosophy discussion).
SO THE IMMEDIATE QUESTION ABOVE: "How would other people divide and tag a
state park whose property line extends offshore?" (The particular case I
have in mind is fairly complex; there are places where the park's boundary
is coterminuous with the high tide line, other places where it's set back
some distance from the water, and yet other places where it extends far
down the foreshore or out into permanent open water.)
TOP-DOWN vs BOTTOM-UP MAPPING
It gets tremendously more complicated if detailed land use and land cover
are needed. Then there will be complex webs of multipolygons, sharing some
but not all of the ways. As a matter of fact, I have a strong preference
for NOT sharing ways among, say, preserve boundaries and things such as
"natural=wood" because they make editing really complicated and seldom
describe the situation in the field. Trees grow where they will unless
humans remove them. They are no respecters of property lines.
Is that what everyone else does? Do even the roughest sketches (drawing the
boundaries of parks, for instance) with webs of multipolygons sharing many
of the ways, so that one set of multipolygons can be tagged for the
protected area, another for the land use, and still another the land cover?
If so, it seems to make for an editing nightmare.
Is there really no way to make these things approximately correct without
metre-by-metre analysis of land cover and land use? (Without detailed
exploration, which may not even be allowed, I surely cannot tell a
"natural" wood from a "managed" one. I can see indications, such as the
predominance of a single species of tree, or a narrow age distribution of
the trees, but these cases can arise naturally as well. And I don't even
know what "managed" means! Is a highly-protected wilderness area 'managed'?
Or does 'managed' imply a plantation? I get conflicting answers.)
What I tend to hear in this community is, "you're going at it all wrong."
Apparently, the only way to approach it is to start with your own back yard
and map only fine details, and then aggregate the details into coarser
structures. I'm getting the feeling that mapping large objects such as
parks, and then filling in the details of what is in the parks, is
something that the community deprecates. I do seem to hear a subtext that I
shouldn't care about where a park is until I've mapped its interior in
If that's really the One True Way of Mapping, then the work that I've done
trying to get public land boundaries in New York sorted out is largely in
contravention to it. I hope that's not the case, and I'm just running into
the sort of special cases that might be expected in a state whose largest
park is larger than the nation of Slovenia.
I suppose, otherwise, I could stick to detailed mapping - the sort of thing
that I did last weekend with
But I really want my map to show where the state land begins and ends, so
that I know where I'm allowed to travel before I get there. And it would be
nice if I don't have to go slogging through beaver swamp to survey ponds
and wetlands before I can have a polygon for the State Forest - which,
after all, is mostly wooded and ostensibly managed for forestry. In
practice, the land there is resource-poor enough that there's little timber
harvest, so it's more a recreational area. (And in practice, few people
want to recreate in that swamp. Now that I've mapped the major features, I
probably shan't be back. The only important aspect was the long trail that
traverses it, and I've got that.)
I won't even get into asking about how to tag seasonally-varying wetlands,
or ones that vary on a longer cycle. Beavers return to the same areas
fairly predictably. They may be grown to meadows or alder swamps, but won't
grow to mature forest before they're flooded again. It's nice to have these
cyclic areas mapped, since they will be muddy but negotiable most years,
and inundated and impassable in some. But that's way more advanced than I'm
trying to get to at present. I'll settle for parcel boundaries, open water,
and trail alignment.
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