[Tagging] Hamlet is always an unincorporated place in OSM?

Fernando Trebien fernando.trebien at gmail.com
Mon Jun 4 23:33:47 UTC 2018


Interesting. I'm not sure if this is a bug in Nominatim or a
misunderstanding of OSM definitions. Let's see:
- Dilermando de Aguiar is a Brazilian municipality with 3308
inhabitants, mapped as an administrative boundary with admin_level=8
with a place=village as its admin_centre node
- Sede is a municipal district, mapped as an administrative boundary
with admin_level=9 sharing the same admin_centre node from its parent
municipality (because it's the main district)
- São José da Porteirinha, currently mapped as as place=hamlet node,
is an urban agglomeration that is spatially disconnected from the main
urban agglomeration of its municipality, with no special political or
administrative status

For each enclosing area, Nominatim computes a rank, using distinct
rules for each country [1], and forms the address line by
concatenating comma-separated names in descending rank order. In this
particular case, it computed [2] rank 16 for São José da Porteirinha
and for Dilermando de Aguiar, and rank 18 for Sede. Thus, it concluded
that Sede (rank 18) is contained in any of the other two (rank 16), of
which only one was chosen.

The documentation of Nominatim [1] suggests that it assumes that a
hamlet will never exist within a village, since by definition in OSM
only certain types of places may be parts of other settlements [3]. It
could have worked if Sede was place=town/city (possibly incorrect or
more correct [4][5]) or if São José da Porteirinha was
place=neighbourhood, which depends on considering the latter distinct
or not from other settlements.

>From the text in the wiki, I understand that any given small piece of
land can be considered part of an urban settlement, part of a rural
settlement, or unsettled land. In Brazil, all municipalities, all
municipal districts and the neighbourhoods with boundaries defined
legally can include any of these types of areas and therefore do not
correspond perfectly to the concept of settlement. If municipalities
are always considered fully settled, any place inside a municipality
must be of a type that may be part of another settlement (such as a
suburb or neighbourhood) and not a type of distinct settlement (such
as a hamlet or village), no matter if there's unsettled land between
remote places and the nucleus of the municipality. If municipalities
are not considered fully settled, it could be argued that their
boundary should not cover unsettled areas (probably undesirable). If
none of the interpretations are correct, Nominatim's ranking system
must have several bugs.

On a side note, Nominatim's default ranking [1] seems to suggest that
towns could be part of cities, though the wiki [3] does not explicitly
suggest this.

[1] https://wiki.openstreetmap.org/wiki/Nominatim/Development_overview#Indexing.2Faddress_calculation
[2] https://nominatim.openstreetmap.org/details.php?place_id=4150595
[3] https://wiki.openstreetmap.org/wiki/Key:place#Populated_settlements.2C_urban
[4] https://en.wikipedia.org/wiki/Subprefecture
[5] (pt) https://forum.openstreetmap.org/viewtopic.php?pid=702045#p702045

On Mon, Jun 4, 2018 at 5:06 PM, santamariense <imagens.sm at gmail.com> wrote:
> Hello everyone,
>
> In Brazil the tag place=hamlet is being used for smallest places, however,
> according to Wikipedia, hamlet may be an unincorporated place. And,
> I've always observed that place=hamlet isn't in the correct hierarchy
> when it's shown in Nominatin.
>
> Example: São José da Porteirinha (
> https://www.openstreetmap.org/node/416766430 ) is shown replacing the
> name of the municipality (admin_level=8) in Nominatin: "Sede, São José
> da Porteirinha, Microrregião de Santa Maria, Mesorregião
> Centro-Ocidental Rio-Grandense, Rio Grande do Sul, Região Sul, Brasil"
> ( https://www.openstreetmap.org/search?query=São%20José%20da%20Porteirinha
> ), where, the correct hierarchy should be "São José da Porteirinha,
> Sede, Dilermando de Aguiar, Microrregião de Santa Maria, Mesorregião
> Centro-Ocidental Rio-Grandense, Rio Grande do Sul, Região Sul, Brasil"
>
> Then, I believe that for Nominatin, all place=hamlet is being taken as
> unincorporated place. There's no place in Brazil that is
> unincorporated. By the correct hierarchy, place=hamlet in Brazil
> should be hierarchly got after level=10.
>
> That's so weird as saying that Nominatin should show a hierarchy like
> State, City, Country instead of City, State, Country.
>
> The question is: Is Nominatin wrong or are we mapping a thing that
> there not be in Brazil and a best tag should be applied? Or maybe a
> new tag like unincorporated=yes/no should be created to complement the
> type of hamlet?
>
> []'s
>
> user santamariense
>
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-- 
Fernando Trebien



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