In the case of the Somerset Levels, is there actually an authoritative
boundary, or is it a fuzzy boundary like a mountain range? Are we
looking for something that doesn't exist, or is this a battle between
differing opinions?
In any case I would suggest using the source and note tags to state
where the OSM boundary comes from, such that a future mapper can judge
whether it can be improved from a better source.
--colin
On 2016-11-26 09:42, Jason Woollacott wrote:
> How inaccurate should something be though? We accept that things will not
> be exact, and GPS tolerances and Bing offsets are a fact of life we need to
> accept.
>
> However we have proper extracts for counties/districts/Parish areas, and all
> the National Parks have extracts.
>
> My issue with the Somerset Levels was that it wasn't the Somerset Levels, it
> was an interpretation of what the levels were, based on NPE contours, (which
> in themselves aren't exact) and was miles and miles off in places. If you
> look at the BBC link the levels stays well below Weston-Super-Mare, yet the
> OSM relationship ploughed right through WSM and out the other side.
>
> -------------------------
>
> FROM: Warin <61sundow...@gmail.com>
> SENT: 25 November 2016 23:23
> TO: talk-gb@openstreetmap.org
> SUBJECT: Re: [Talk-GB] Somerset Levels
>
> If you think that the data must be 100% accurate you will have a blank map
> ... therebe dragons.
>
> The world standard for 1 kilogram mass is an artefact (a physical object) in
> Paris.
>
> You might think that it is 100% accurate and you'd be wrong. The surface
> corrodes, gets dust on it .. that adds weight .. so you polish it .. how much
> do you polish it? Too much and you remove weight, not enough and you leave
> weight behind.
>
> Everything has some level of uncertainty.
> The JOSM way simplifier is set for a maximum displacement of 3 meters. Is
> that acceptable?
> Remember that the original data has some level of uncertainty too. Typically
> a GPS would be 10 meters. Average a few and you might get down to 5 meters.
>
> Personally I'd rather have an indication that something is there even if
> 'inaccurate' ... compared to a blank bit of paper.
>
> On 26-Nov-16 09:18 AM, Dave F wrote: Good.
>
> Bearing in mind that nothing* in OSM is 100% accurate (& the Somerset Levels
> do exist), how accurate do you need the data to be for them to be good enough
> for inclusion?
>
> * No, honestly, it's not.
>
> DaveF
>
> On 25/11/2016 15:12, Jason Woollacott wrote:
>
> in the description i remember it stated it was based on the 10ft and 25ft
> contours.
>
> -------------------------
>
> FROM: Dave F <davefoxfa...@btinternet.com>
> SENT: 25 November 2016 14:07
> TO: Jason Woollacott; talk-gb@openstreetmap.org
> SUBJECT: Re: [Talk-GB] Somerset Levels
>
> Not 100% sure, but wasn't it based on contour levels?
>
> On 24/11/2016 17:35, Jason Woollacott wrote:
>
> HI,
>
> Yes, I removed this as I felt that it was incorrect and did not reflect the
> conditions on the ground. It was specifically removed under one change
> back in September 2016, whilst I was working on addressing some of the other
> mapping errors around that area. The Change was deliberately done under
> one change set, so that it should be easily restored if there was ever a need
> for it. However the boundary was a guestimate at best and did not reflect
> the actual area of the Somerset Levels, (going through Bridgwater & Weston
> Super Mare).
>
> An example of what is really defined as the Somerset Levels is here
> http://www.bbc.co.uk/news/uk-england-somerset-26080597 but there isn't an
> extract, that I've found, that we could use for tracing.
>
> I'm not sure what benefit reinstating this change would give.
>
> Jason (UniEagle)
>
> -------------------------
>
> FROM: Dave F <davefoxfa...@btinternet.com>
> SENT: 23 November 2016 12:55
> TO: talk-gb@openstreetmap.org
> SUBJECT: Re: [Talk-GB] Somerset Levels
>
> It appears it was deleted by user UniEagle
> http://www.openstreetmap.org/changeset/42348215
> You may wish to contact him & ask to participate in this discussion.
>
> FYI
> Undeleting using Potlatch 1
> If you know a location where the boundary was, zoom in as close as
> possible, then amend the URL & open in P1. This is an example near
> Bridgwater:
> https://www.openstreetmap.org/edit?editor=potlatch&#map=16/51.1414/-2.9724
>
> Hit the 'U' (for undelete)
> Then wait... & wait some more.
> Eventually some red lines should appear (the server can be temperamental
> & refuse to play)
> Select the way of the relation.
> In the preset list at the bottom of the screen there should be a red box
> with 'Click to Unlocked' written in it.
> Click to unlock (again, this may take some time)
> Save & close.
> Open your preferred editor to check it was properly undeleted.
>
> DaveF
>
> On 23/11/2016 00:45, Nick Austin wrote:
>> Does anyone know what happened to the Somerset Levels super-relation?
>>
>> I don't know how to search for deleted stuff so I can't look up it's
>> history to see what happened.
>>
>> TIA.
>> Nick.
>>
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