[Tagging] Mapping nonexistent paths

Bert -Araali- Van Opstal bert.araali.afritastic at gmail.com
Tue Mar 23 10:30:43 UTC 2021

I am sorry but I am still not seeing the advantage or added value to 
introduce keys or values to indicate that something is "less visible" or 
"less verifiable" or virtual or whatever you call it. I can't fit it in 
the model that exists in my mind how we map things, especially ways in OSM.

All highways, all their connections, all rivers are virtual in OSM, all 
routes are virtual.  We map them by drawing and connecting ways across 
surfaces.  A pavement that stops "early" doesn't mean the path, the 
route people walk stops there.  That is insufficient completeness in the 
mapping. Every highway or lane is mapped with a "virtual" line in the 
middle, the "virtual" route people or vehicles follow across a surface, 
be it asphalt grass or whatever.
Ferries and boats move across a lake on "virtual" routes, they just 
follow a path on the water surface, in many cases not aligned by buoys 
or other means.
The same for coastlines, the "virtual" coastline is where the median is 
between the salt and fresh water.  In cartography many times just a 
straight line.  You want to indicate the river connects to the water 
body and which route boats or ships follow, you map it, with our present 
complete "virtual" waterway schemes.
I still have to see the first example where that doesn't apply or is not 
described nicely in our wiki.

What does adding an additional tag add to this concept ? Makes it more 
complex to the mapper, because he has to add a tag for something 
considered more virtual in an already virtual scheme ? What is the added 
value for the mapper, I see none.
What is the added value for the router ?  I can't imagine even one?  Do 
you think routers will evaluate the virtual tag, no they just look at 
the ways, the routes in general that are already there.  Knowing that it 
is perceived as more virtual by some has no added value for the router.
For the renderer, other data users ? Any added value for a virtual or 
invisible tag in comparison with what we already have ? I can't find any.
Please show me an example where the current tagging would be considered 
less favourable to be used as is ?

So, thank you for making this proposal, you made some nice examples 
which we could maybe add to the highway page.  But it's just examples 
how OSM provides a bright and consistent way to map complex realities 
and behaviour, AS IS. It works, use it as intended, don't make it more 
complex by adding tags without added value.


Bert Araali

On 23/03/2021 12:38, Martin Koppenhoefer wrote:
> sent from a phone
>> On 23 Mar 2021, at 10:23, Niels Elgaard Larsen <elgaard at agol.dk> wrote:
>> Can anyone give an example of such a sophisticated router available to OSM users?
> the routers don’t have to be sophisticated if you connect highways to polygon highways, it’s sufficient for most cases to route around the borders (will be a little bit longer, but mostly not have practical consequences for the suggested route)
> Cheers Martin
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