On 2015-03-25 08:12, Martijn van Exel wrote:
On Wed, Mar 25, 2015 at 3:00 AM, Minh Nguyen wrote:
On 2015-03-24 13:57, Martijn van Exel wrote:
More importantly though, there is an authoritative source for
official administrative boundaries that can be easily accessed by
anyone: TIGER[1]
You mean the way TIGER is an authoritative source for road
centerlines? TIGER's boundaries vary in quality just as its roads
and railroads do. I've taken quite a few imported municipal
boundaries, lined them up with road easements or hedges between
farms _when that is obviously the intent_, and deleted extra nodes.
These borders become far more accurate and precise in OSM than in
commercial maps, which regurgitate TIGER boundaries verbatim.
The most authoritative source for most U.S. land borders, going all
the way down to the parcel level, is a legal prose definition in
conjunction with any number of monuments on the ground. Both metes
and bounds and the Public Land Survey System rely on monumentation.
A monument may be a major road or as obscure as a small iron pin
embedded in that road, but even that pin is verifiable if not
particularly armchair-mappable.
If you're lucky, you can find an Ohio city limit's legal definition
in county commissioners' minutes when an annexation is proposed. The
most authoritative data representation is the county GIS database,
which anyone can easily access -- for a fee. After paying the county
for that database, you might well forget about OSM, because it's
also the authoritative source for road centerlines and names.
That is actually not what I meant, but I could have been more precise. I
guess this turns into a discussion of what 'authoritative' actually
means. This is different things to different people. As OSM becomes
better, increasingly folks will start looking at us for
authoritativeness, which would make sense because everything is
(supposed to be) verified on the ground. Because administrative
boundaries have legal implications, the authoritative source will need
to be someplace outside of OSM. It may actually hurt OSM down the line
if we include information that suggests authoritativeness we cannot
provide.
OK, thanks for clarifying. One risky use of administrative boundary data
at the local level would be for tax purposes. Obviously we don't want
people relying on OSM to decide whom to pay taxes to. That's why we have
a disclaimer. [1] It should get more prominence. Wikipedia's legal and
medical disclaimers are two hops away from every article, but ours is
two hops from the wiki's main page only. At least consumer-focused
redistributors of OSM data tend to have more accessible disclaimers.
[1] http://wiki.osm.org/wiki/Disclaimer
Sure, but vernacular and official neighborhood objects would then need
to be represented differently so folks can tell them apart and know what
they are dealing with.
I agree entirely, and I think OSM is already set up for these
distinctions. If you see a boundary=administrative admin_level=10
relation on the map, you'd expect it to be an official (aka
administrative) boundary, not a vernacular one. If you see a
place=neighborhood POI with the name tag, you'd expect both definitions
to be roughly equivalent. A purely vernacular neighborhood would be a
POI probably tagged with loc_name instead of name.
--
m...@nguyen.cincinnati.oh.us
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