[Talk-GB] Are Northern Ireland, Wales & England 'states'?

Dave F davefoxfac63 at btinternet.com
Tue Aug 22 12:09:24 UTC 2017


OSM is geospatially aware. I'm unsure why there's a reluctance to use it.

is_in tags are far more "incomplete and imperfect" than boundaries.
Boundaries are maintained far more than the antiquated is_in:*.

*Every* entity will require a full set of is_in tags to be workable.

If an entity is in "no-mans-land" of boundaries, it will be in 
"no-mans-land" if tag with is_in, Using geospatial calculation with 
boundaries it will know it's 'outside' but be able to find the nearest 
area. Describing it a 'near to...' isn't perfect but better than nothing 
which is what you'd get using is_In.

DaveF


On 22/08/2017 12:23, Colin Smale wrote:
>
> Let's have some use cases out on the table... if my location is 
> {lat,lon}, where am I? What answer am I expecting? Postal address? 
> Town or other settlement? The local council? What would a "local" answer?
>
> In the UK, the hierarchy of admin boundaries is incomplete and 
> imperfect - there are unparished areas, and combined authorities for 
> example. There are so many black holes in the UK - where you are in 
> no-mans-land "between A and B but in neither." If nobody lives there, 
> is it actually necessary to be able to say where you are?
>
> If you ask people where they live, they will probably talk about the 
> county level and the settlement/town/city, but the informal boundaries 
> of these settlements will likely not follow the administrative 
> boundaries. In fact, it may not be possible to agree a polygon with a 
> sharp boundary of what constitutes a settlement with a given name. 
> Most place=* polygons in OSM just follow the boundary of the built-up 
> area.
>
> So I see a possible role for is_in - to help out geocoding where 
> geometrical methods lead to an undesirable (though accurate) result.
>
> //colin
>
> On 2017-08-22 12:57, Dave F wrote:
>
>>
>> This is a reply to a Q. I posed on Talk. Nominatum clearly prefer 
>> boundaries to is_in & say it's not heavy processing:
>> https://lists.openstreetmap.org/pipermail/talk/2016-August/076596.html
>>
>> As UK boundaries are sure be updated in OSM, keeping the secondary 
>> is_in 'cleanly managed' will be a major task.
>>
>> On 22/08/2017 09:38, Lester Caine wrote:
>>> On 12/08/17 13:12, Dave F wrote:
>>>> I also think the 'is_in:country_code' along with all 'is-_in' tags are
>>>> redundant if there's a boundary tag..
>>> In the past I thought that the is_in element was something of a problem,
>>> but it does have a place when one remembers that OSM is all about the
>>> data. "if there's a boundary tag" is the problem here if one is
>>> extracting a set of data? Processing a number of boundaries around a set
>>> of objects takes time, while cleanly managed is_in:admin_area with a
>>> proper hierarchy allows a much quicker lookup of information such as -
>>> in the case of the the UK - parliamentary boundaries, wards, historic
>>> county, NHS admin area and so on without having to physically draw every
>>> fine detail of these ever changing boundaries. BUT it only works well if
>>> there is a well defined hierarchy so tagging is_in:gb-ward
>>> http://geoportal.statistics.gov.uk/datasets/417e93f21c5c419283ac23abc8eedcce_0
>>> gives all this data in a format we can freely use as with the other
>>> 'boundary' data.
>>>
>>> It is just a pity that 'postcode' is so badly organised that it quite
>>> regularly straddles these other boundaries, but is_in:gb-postcode would
>>> remove the need to add all of the associated address data to every
>>> object on a particular street, and for the vast majority of postcodes it
>>> WOULD also identify all of the other is_in: data at a higher level. It
>>> just needs an object defining is:gb-postcode and is:gb-ward to provide
>>> all the hierarchy ... without overloading the server with searches for
>>> all of the boundaries intersecting the original dataset?
>>>
>>> Of cause I am also still looking to maintain access to historic data,
>>> and this model makes it easy to check start and end dates of
>>> is:gb-postcode and is:gb-ward without having to maintain all of those
>>> boundaries actually in the base dataset - something which the majority
>>> of users seems to have decided against :(
>>
>>
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>
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