[Tagging] sidewalks and tagging for the renderer

Georg Feddern osm at bavarianmallet.de
Thu Apr 12 07:26:19 BST 2012

Am 11.04.2012 11:35, schrieb Martin Koppenhoefer:
> in the case of parallel ways it is impossible to tell whether you can
> filter them out or not (there could be a separation or they could be
> on different height levels), especially if people are mapping
> sidewalks the same as separated footways.

Thats a point - and the differentiation should be really considered in 
the tagging.

>   My main concern is routing,
> not rendering. I wouldn't take them into account in routing, because I
> feel you would get worse results.
> E.g. 100 m South of the spot you posted above:
> http://www.openstreetmap.org/?mlat=53.865988&mlon=27.651201&zoom=18&layers=M
> Imagine you stand there and want to go to the parking on the other
> side of the road:

You take very 'short way' examples - to show the point of concern, thats ok.
But these are examples where - I think - no one would even consider to 
use routing.
On the other hand:
Use 'practicable' examples (far longer ways) and you will see, that many 
(not all) of these 'problems' fade away, because the routing will use 
those crossings anyway and lead to the right side before .
If there is no sidewalk on the destination side or another adequate 
footway - it will use your approach anyway ...
A person who can see the situation can see the routing too - and may 
shorten the route on his own risk.
A person who does not .. well, I would not recommend them a shorting 
anyway ...

> Another similar issue is that with these sidewalks people often don't
> connect crossing footways to the street, they only connect them to the
> sidewalk. There are examples for this also in your area, so
> unfortunately simply omitting them won't do the job either, because
> you would get gaps near crossings.

A crossing footway over a street with bothside sidewalk must not always 
be connected to the street - carriageway and sidewalk are considered as 
different transport route with different usage then.
For routing there is no need to connect them.
For renderer there is no need to consider which is top or bottom - he 
may choose  itself by usage preference. (Distinction of bridge and 
tunnel presumed.)
The signal points or the 'consider a hazard' points may be outside of 
the crossing point itself.
Connections are only needed at points where you can really use a parting 
transport way (which may be a street without sidewalk).

>> Third, try to cross these not on the crossing staying alive:
>> http://upload.wikimedia.org/wikipedia/commons/thumb/1/14/Partyzanski_praspekt_8.jpg/300px-Partyzanski_praspekt_8.jpg
>> http://kp.ru/f/4/image/26/67/396726.jpg
> I'll do next time I visit your town. What should be the problem? You
> wait until there is no car coming or all cars stop and then you cross.

Yes - I see, you have _seen_ the point already. ;-)


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