[Tagging] How to tag small canals?

Warin 61sundowner at gmail.com
Sat Aug 18 08:33:38 UTC 2018

How are data consumers going to use the data ???

Not much point in it for them I'd think.

For mappers that come along later it may be a usefull guide for 
comparison with their measurements.
But few mappers will be bothered entering it so I again don't see much 

I'd think tagging like


might be the way to go?
The uncertainty coverage factor of 1 (or standard deviation for a 
Gaussian distribution) could be stipulated as part of any documentation.

On 18/08/18 17:53, Peter Elderson wrote:
> Sure. But is there a standard method to indicate this uncertainty in 
> OSM, which can be processed by data consumers?
> Mvg Peter Elderson
> Op 18 aug. 2018 om 01:35 heeft Warin <61sundowner at gmail.com 
> <mailto:61sundowner at gmail.com>> het volgende geschreven:
>> What you are trying to refer to is 'measurement uncertainty'.
>> For a non professional rough guide;
>> https://en.wikipedia.org/wiki/Measurement_uncertainty
>> Naturally formed water way widths may have a great deal of variation 
>> along their widths .. and so the uncertainty will be very high unless 
>> specified along short segments.
>> On 18/08/18 09:11, Peter Elderson wrote:
>>> It would not be that hard to add a precision to a measurement. Any 
>>> measurement. Maybe there already is a standard method for that?
>>> Mvg Peter Elderson
>>> Op 17 aug. 2018 om 20:50 heeft SelfishSeahorse 
>>> <selfishseahorse at gmail.com <mailto:selfishseahorse at gmail.com>> het 
>>> volgende geschreven:
>>>> On Friday, August 17, 2018, Christoph Hormann <osm at imagico.de 
>>>> <mailto:osm at imagico.de>> wrote:
>>>>     On Friday 17 August 2018, SelfishSeahorse wrote:
>>>>     > Of course we could just use width=*, but it's not always easily
>>>>     > possible to measure the width (e.g. in a forest) and sometimes it
>>>>     > changes often.
>>>>     I would translate this into "i want a subjective non-verifiable
>>>>     classification system but i hide this by defining pro forma
>>>>     verifiable
>>>>     criteria for the classes".
>>>> A classification based on width is arbitrary, but i don't see why 
>>>> it be subjective.
>>>>     If you want to map the river width tag width=*, if you don't
>>>>     want to map
>>>>     the width then don't create classes based on width thresholds.
>>>> Imagine a stream/brook in a forest, not visible on satellite 
>>>> imagery. You can't measure its width on site (because you don't 
>>>> have the equipment or because the soil at its sides is marshy), but 
>>>> you know (estimate) that it's wider than 1 metre, but less wide 
>>>> than 3 metres. In my opinion it's better to have that information 
>>>> that none.
>>>> If you enter width="1 m - 3 m", data users very likely won't 
>>>> understand it. However if you enter width="2 m", the width value 
>>>> pretends to be exact. Besides it is very unlikely that someone else 
>>>> verifies that value, considering the fact that less than 1% of 
>>>> waterway=* tags have a width=* tag.
>>>> _______________________________________________

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