[Tagging] Can OSM become a geospacial database?

Eugene Podshivalov yaugenka at gmail.com
Wed Dec 5 15:49:29 UTC 2018


This email is a forward message of this forum topic
https://forum.openstreetmap.org/viewtopic.php?id=64704

I guess this topic has been raised may times already but let me add to it.
Right now OSM is a collection of dots and lines with some generic tags for
rendering them on a map. They do compile into nice maps but does it really
work when it comes to searching for objects of real life categories? Let's
look into some examples.
* place=city/town/village/hamlet/isolated_dwelling stand for settlements of
some pupulation ranges. But each country has its own categorization of
settlements which may absolutely differ from the suggested gradation.
* waterway=river/stream are used for natural relatively large or small
waterways. But the notion of river may differ from country to country and
they may have a much wider range of categories then just these two ones.
* amenity=school/university/college have some generic notion of secondary,
higher and further edicution institutions. But again each country has it's
own categorization of educational institutions and in some cases it even
contradicts the suggested tag names, e.g. in Russia they have colleges as
something intermediate between high school and university.

To wrap it up it is hard to impossible to get objects of some real live
category from OSM database in order for example to hight light them on a
map or to list them in search results.

There are two workarounds used right now. The first one is to bind some new
tags to local categories e.g. school=high_school, school=college. This
approach is very contradictary because it is recognized only locally and
may conflict with notations in other countries.
The second one is to put category name into "name" tag, e.g. "Liberty
avenue", "Blue lake", "South park". This approach works pretty fine until
you think of applying it to everything, e.g. "Manchester" would become
"Manchester city", all shops would become "[name] shop" and will be
rendered as such on maps or otherwise additional algorithms will need to be
coded for rederers to decide whether to cut a category name from the
displayed name or not for each particular country.

I invision the following solution here.
* First of all, the "name" tag should containt proper name only.
* Secondly, introduce a new tag for the real life language specific
category name. I know that "name:prefix/postfix" key was originally
introduced for another purpose but it can be a candidate here as well. Note
that in some languages the place of category name relative to the proper
name matters.
* Thirdly, in order to make the life of renderers simple, introduce one
more tag for holding the name which can be displayed on maps as is without
any modifications, e.g. "display_name". This tag may contain whatever
content is considered locally appropriate specifically for rendering on
maps. For example, it may contain proper name with category abbriviation
like "r. Missisipi" or proper name with category full name like "Liberty
avenue" or if an object has no proper name but is worth being labeled like
"police station". Locally agreed upon rules should prevail here and if
somebody needs another format he is free to utilize "name" and
"name:prefix" tags the way he likes it.
If proper name is considered good for rendering without any modifications
like "Manchester" city then display_name can be missing.

Here are a couple of collective examples:
* highway=residential + name:ru=Независимости + name:prefix:ru=проспект +
display_name:ru="пр-т Независимости"
* waterway=river + name:de=Elbe + name:prefix:de=Fluß (no "display_name"
tag becase they usually display only proper names of rivers on maps in
Germany)
* place=city + name:en=Manchester (no "display_name" tag because it is
equal to "name", and no "name:prefix" tag if and only if the values in
"place" tag correspond to the real life settlement categories in US)

Regards,
Eugene P
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