[mkgmap-dev] Missing ways part 2

Mon Oct 18 23:44:28 BST 2010

Marko wrote:
> Good idea.

Thank you.

> Would you happen to have an idea how to tag (and in mkgmap) hide a
> highway=service tunnel for accessing a railway tunnel?

This is very much a special case. It is the result of several factors
working together. One of the factors is that Garmin devices do not give
a clear indication of whether ways that cross are connected. It is
possible to use custom style and .TYP files to draw distinctive lines
for bridges and tunnels, and this would make things clearer.

I've looked at the tagging of way 69679696 and it looks fine. You would
hide the way by omitting it, as with underground railways, but you need
a test that you can put in the style file. Naturally, this test must not
cause the loss of ways you want to keep. You could perhaps add a tag
"note=mkgmap omit" without stretching the conventions of OSM too far. I
can't think of any other recognised tag you could use. If you tagged
"mkgmap=omit" you would be tagging for the renderer and that is
definitely discouraged.

Another possibility would be to test for a combination of the tags that
are already there. I have just downloaded finland.osm.pbf and used

osmosis --rb finland.osm.pbf --tf accept-ways highway=service --tf accept-ways tunnel=yes --tf reject-relations --un --wx service_tunnel.osm

to extract ways tagged both highway=service and tunnel=yes. The osmosis
run took 40 seconds. I loaded the extract into JOSM and there are 271
ways. I could readily see that there are several similar access tunnels
in the Helsinki area. I used the search function to select all the ways.
I then selected the key "access" in the list of properties, clicked
edit, and clicked the drop-down triangle next to Value in the dialog
box, and it told me that 33 of the ways are marked private, 17 have
other values (and the rest do not have an access tag). It would not be
impractical to look at each of the 33 private ways. In this way you
could decide whether to test for access=private, whether to test for
something else, or whether to add "note=mkgmap omit" to specific ways.
(It may not be practical to edit such an extract because any relation
memberships would be lost when you uploaded, and if you retained
relations in the extract, it might overload JOSM. You'd need to try it
and see. Save your edits to a local file before clicking upload,
because it is the validator which has the most problems with big data
sets.)