[mkgmap-dev] routing / address search: What makes a road (, house number, etc.) belong to a city (, country, etc.)

Tue Apr 21 06:49:05 BST 2009

Hi there!

As we have regular discussions about $SUBJECT on the German OSM list,
I'd like to know about the current state within mkgmap and your opinions
on that.

Things which come to my mind to make things belong to others so far, are:

1) tags on the child like is_in or addr:street/addr:city
2) place and boundary polygons for the "parent"
3) relations

Can you give a short summary which of those are currently used and which
could probably make your life easier in the future? Especially taking
into account a real, working address search with house numbers, post
codes and all that...

(I'm personally in strong favor for 2) when it comes to street->city and
3) when it comes to housenr->street)

Some observations I made with my mkgmap cards in Bavaria, DE:

* For the "road-name-pois", things look quite ok. All streets I looked
up so far are labelled with the correct suffix ("/City"). However, for
quite some, I've no clue how mkgmap figures this out - simply searching
for the next city node?

* On the other hand, with mkgmap cards loaded, my Nüvi seems to have no
idea about streets being within or without a city. In Germany, a
primary/secondary/tertiary road within a city is normally restricted to
maxspeed=50, but to maxspeed=100 when it's outside - so we don't tag
this explicitly. However, my Nüvi always expects me to go with something
like 70km/h on primary roads - independent where I am. This makes ETAs
in cities terribly wrong. It expects you to cross a city in 5 minutes
which is usually quite ... optimistic.

* For the "real address search", things seem to be quite
indeterministic. Sometimes, a street is listed as part of "City, City",
sometimes the city is prefixed with a long list of post codes. I'm even
quite sure that I also saw "Suburb, City" in the past - however I'm not
able to reproduce this with r1006 at the moment. I'm quite sure that is
based on inconsistent data within OSM, but how exactly?

TIA!

--
Gernot