[Talk-us] tagging a national forest boundary

Zeke Farwell ezekielf at gmail.com
Fri Oct 1 22:58:14 BST 2010

This exact question is the reason why I haven't imported the Green Mountain
National Forest in Vermont (well also the fact that I haven't figured out
how to convert Shapefiles to OSM format yet, but anyhow….).  My research
leads me to believe the the National Forest Boundary is simply the area
within which the USFS has a mandate to acquire land.  In the southern part
of the GMNF the USFS only owns about 50% of the land within this boundary,
but they add more each year.

Anyway I've been trying to decide how to map this situation.  It seems to be
the case with many national forests on the east coast since they were
created in areas where much of the land was already privately owned.  Seems
we need a way to tag the official outer boundary of national forests (and
parks?) as there is often a sign marking these boundaries on major roads
even if you aren't yet entering USFS owned land.  The best I can come up
with is to use boundary=national_park for the outer boundary and then use
landuse=forest on a multipolygon that excludes the inholdings. This would
render on Mapnik with a green dashed line on the boundary, dark green for
USFS land, and light green for inholdings.


On Thu, Sep 30, 2010 at 10:50 PM, Nathan Edgars II <neroute2 at gmail.com>wrote:

> On Thu, Sep 30, 2010 at 9:52 PM, Greg Troxel <gdt at ir.bbn.com> wrote:
> > I think you two might be talking past each other.
> >
> > I am slightly fuzzy on multipolygons, but I think the notion is that a
> > multipolygon has a number of outer rings, and a number of inner rings,
> > and it defines the area that consists of points within an outer ring and
> > not within an inner ring.
> >
> > So in the national forest/inholdings case, I think you have a polygon
> > (closed way) that is the boundary (typically drawn strongly on a
> > traditional topo), labeled as the forest boundary.  Then you have a
> > polygon for each inholding, with no particular tags required.  And then
> > a multipolygon with the forest boundary as outer and all the inholdings
> > as inner.
> Bloody hell, I know this. The problem is that some of the inholdings
> touch the boundary, so they're actually outer ways (and the portion of
> the boundary there is nothing):
> http://www.openstreetmap.org/?lat=28.99352&lon=-81.64891&zoom=15&layers=M&relation=1202373
> Yet the boundary is still something official.
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