On 08/19/2015 05:29 AM, Nathan Mixter wrote:
In any discussions about land use and land cover, we should look at
what organizations have done and how they have mapped ares. For
instance, in USGS imagery in JOSM you can see how they render borders
with just a dashed line and let the land cover have various shades of
color on top of it.
The U.S. Forest Service has a distinct classification for mapping
vegetation within the forest. And the USDA differentiates between use
of forest land and forest cover
(http://www.ers.usda.gov/data-products/major-land-uses/glossary.aspx).
Here is how the USGS defines land use and land cover
(http://www.mrlc.gov/nlcd92_leg.php and in more depth at
http://landcover.usgs.gov/pdf/anderson.pdf). Not sure how other
countries map land use and land cover, but this is a sample from what
the U.S. does.
From
http://www.ers.usda.gov/about-ers/strengthening-statistics-through-the-interagency-council-on-agricultural-rural-statistics/land-use-and-land-cover-estimates-for-the-united-states.aspx#h
Land use and land cover are often related, but they have different
meanings. Land use involves an element of human activity and reflects
human decisions about how land will be used. Land cover refers to the
vegetative characteristics or manmade constructions on the land’s
surface.
I hear a lot of argument here, and much of it is philosophizing. Let me
offer another argument. Deficiencies in the standard rendering are
leading us to impose constraints that do not exist. The very idea that
we should have to cut out watercourses and highways from a National
Forest to show it correctly on a map is absurd. If the renderer cannot
cope with the idea that the Elm Ridge Wild Forest (a protected area -
and specifically an area of state ownership with public access for
recreation and harvesting of fish and game) lies partly within and
partly outside the Catskill Park (a different sort of protected area,
not all under state ownership) and in turn has several bicycle corridors
(an area of less protection) overlaid upon it, then it cannot cope with
the messy reality that I work with locally.
Since I render my own maps, let me begin by observing: THE LACK OF
CONSENSUS ON THESE ISSUES MEANS THAT I DO NOT USE OSM AS A DATA SOURCE
FOR PROTECTED AREA BOUNDARIES. I go to alternative, mostly government,
data sources for the boundaries of government and other protected lands
and use them for map production. I simply cannot cope with wholesale
retagging of these areas every few months as each new tagging scheme
comes through. WE NEED TO REACH SOME SORT OF STABLE CONSENSUS, at least
one that lets us produce medium-scale maps suitable for general use
without running on a hamster wheel of patching renderers to adapt to
changing tag schemes.
I've half come around to the position that National Forest boundaries
don't belong in our database at all. They're often not any more
observable on the ground than any other property lines - and I believe
that we reached a consensus that delineating land ownership is outside
the scope of OSM. (Am I wrong about this?) In fact, the reason that I'm
able to ignore OSM on the point is that most of the data I need is
available in authoritative form from the agencies that manage the land.
Unfortunately, some of the smaller agencies (mostly county and municipal
agencies) still haven't moved forward into using GIS, or simply don't
have the resources to make what GIS data they have available to the
public, so there's still some amount of measuring on paper maps. I'd
done a few local nature preserves that way (along with cross checking by
hiking to corners and collecting GPS waypoints), and it had been
convenient to use OSM as a store for the data so collected, but I'm
willing to give that up and go back to holding the data privately and
rendering them as another layer - doing an export from OSM to my own
data store. Again, the features are hard to observe in the field. It's
quite an interesting hunting expedition, trying to find the corners of a
county nature preserve where the adjoining landowner doesn't trouble to
post the land. Sometimes it involves trying to locate survey pins with a
metal detector in dense forest.
Since we don't have a good general policy for OSM maintenance of data
where the authoritative copy is elsewhere, OSM really simply becomes the
convenience of one stop shopping. I enjoy having that convenience, and
so do many other users. But for some of the data, it simply costs too
much time and effort to negotiate the minefield of tag wars.
And I still claim it's largely because of the renderer.
So now let me move forward to specific rendering suggestions - noting
that that I'm here as a field mapper (I mostly do hiking trails and
associated facilities, and for the most part don't armchair-map
anything), a consumer of OSM data (I produce my own maps for my
GPS-equipped smartphone, because I find them
