[Tagging] importance=* tag (for transportation etc)

Alexander Matheisen AlexanderMatheisen at ish.de
Fri Mar 25 18:10:12 UTC 2016

Am Freitag, den 25.03.2016, 16:36 +0000 schrieb Andy Mabbett:
> On 25 March 2016 at 12:19, Alexander Matheisen
> <AlexanderMatheisen at ish.de> wrote:
> > Am Freitag, den 25.03.2016, 11:26 +0000 schrieb Andy Mabbett:
> > > On 20 March 2016 at 00:12, Alexander Matheisen
> > > <AlexanderMatheisen at ish.de> wrote:
> > > 
> > > > If you have a look at the highway=* tagging: This scheme is
> > > > subjective,
> > > > but there is no alternative.
> > > 
> > > Poppycock.
> > 
> > Why?
> For the reason I gave in an earlier post: it is often an objective,
> verifiable legal designation.

No, see my recent post: https://lists.openstreetmap.org/pipermail/taggi

> > > > It is not possible to calculate the importance
> > > > of a station just by some values.
> > > 
> > > How do you calculate it, then? Rolling dice?
> > 
> > I do not use any calculation based on measures?! My proposal (seems
> > that you did not read it) uses a list of characteristic criterias
> > for
> > each category.
> You seem to mean different things by:

> Please define your terms.

Sorry, I am no native English speaker, so sometimes I may have problems
to find the right term for my ideas.

> * values
> * measures

For me these terms are almost equal: Numeric values which are neutral
facts and a measurable (e.g. by counting things). For example the
number of passengers, population, etc.

> * characteristic criterias [sic]

Oh, that is a strange term. What I meant was "characteristic
properties". A list of properties that are typical and representative
for objects of a category. An object must not have all of these
properties; these properties help the mapper to decide which category
is the most appropriate for an object.

Examples: "Stations of category xyz typically are big traffic hubs
served by highspeed trains" or "Typically, these controlled-access
highways have a minimum of two lanes in each direction that are
separated by a barrier." from 

> > The scheme I propose can be compared to the place=* scheme.
> > This definition also mentions "important", so where is the
> > difference
> > to the importance proposal?
> The former does not try to quantify importance. It uses the term
> descriptively in the page about the key, not as the key.

So if I understand you right, your main point of critique only concerns
the name of the key? What about tagging stations with e.g.

> > > > I also see problems in getting some of the proposed values. For
> > > > example, the amount of passengers or trains per time is
> > > > difficult
> > > > to
> > > > measure for a mapper and is not easy to be checked by other
> > > > mappers.
> > > 
> > > Please explain what measure you are using, that is *more easily
> > > checked* by other mappers.
> > 
> > If you think that the number of passengers or trains is easy to map
> > in
> > a larger scale, then please describe how you would map these
> > values.
> Please answer my question.

As I described I would not use information such as number of
passengers, etc. but just a single tag that classifies a station.

> > If you just calculate the importance from a list of measurable
> > values,
> > you may get good results with a complex algorithm that recognizes
> > many
> > aspects. But then it is very difficult for a mapper to understand
> > why
> > station A was ranked more important than station B, and it is also
> > difficult to influence the ranking if it is wrong. That is what I
> > mean
> > with transparency.
> So long as the algorithm is published, it would be entirely
> transparent.

Yes and no.

Of course if is transparent in the way that it is possible to
understand how this ranking algorithm works and what is returned.

But still intransparent is the result itself of this algorithm. Think
of an algorithm that calculates the importance by recognizing
passengers per day, number of platforms and number of trains. This
algorithm will combines these values and return a numeric value. And
this numeric value is not transparent because for itself it does not
contain any information. It is just a relative information. Compared
with the values of other stations it is possible to say that station A
is more important than station B.

But with a tag like importance=* you have a human-readable information
about the importance of a station.

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