[mkgmap-dev] Style rules and 'generated' tags

Tue Jul 7 17:40:40 BST 2009

2009/7/7 Torsten Leistikow <de_muur at gmx.de>

> Steve Ratcliffe schrieb:
> >> highway=* {set tag_a=yes}
> >> tag_a!=yes {set tag_b=yes}
> >> tag_a=yes [0x01 resolution 20]
> >> tag_b=yes [0x02 resolution 20]
> >> highway=* [0x03 resolution 20]
> >>
> >> Will all highways be converted to 0x01, 0x02 or 0x03?
> >
> > My guess was 0x01.  But it turns out that I was wrong :)  Actually
> > it is not a valid style because you can't have tag_a!=yes all by itself.
>
> In OSM you can have any tags you like, so there is no reason, why such a
> style would be invalid (e.g. you could use such a scheme, to set all
> highway=footway to highway=path and foot=designated).
>
> And I think, if I would change the second line to
>
> highway=* tag_a!=yes {set tag_b=yes}
>
> it wouldn't change anything, or would it?
>
> I am still trying to figure out, how the rules are working at the
> moment. So what is the result of the above? (I haven't tried it myself.)
> Which lines are processed in which are left out?
>
> What would happen, if the second lien would be changed to the following:
> tag_a!=yes {set tag_a=no; set tag_b=yes}
>
> > It seems that the action rules are being used a lot more than I thought
> > going some way beyond what they were designed for.  We need to look at
> what
> > the actions are being used for.  I get the impression that a lot of it is
> > to normalize inconsistent tagging, so perhaps we need a separate stage
> > where that is done explicitly.
>
> I don't know, what is possible with the action rules right now, since I
> am still trying to figure out, how they are working.

you can have tags only, but they dont create a copy of the map. whereas
lines seem to be taken for polygons if not asked for in the style-file (i.e.
if you set have_riverbank=yes to display water in the polygon file and any
simple line is joined to become a polygon, often with the generated water
layed over large areas, lines will only be drawn if they are somehow
attached to highway=* & asdf

also when creating style-rules the order is important. highway=* has to be
first, or else some rules will not work so while asdf & highway=* [0x01
resolution 24] does not work, highway=* & asdf [0x01 resolution 24]  does
work. might be that this problem only appears on more complex rules (I have
a ruleset of around 10.000 checks running, and needed to tweek the position
of highway=* quite a lot until it actually showed up. I consider the
style-rules to be quite buggy therefore.

>
> Right now I am trying to use the action rules, to generate a bicycle
> routing map, which uses the Garmin-Navi in car-mode, because of the
> better routing algorithms. Therefor I am tweeking the road classes and
> the access restrictions.
> So basically I am trying to use the action rules as a preprocessor for
> the OSM data.
>
> Oh, and by the way: Would it be possible, to add support for a "txt"
> extension for the style files? It is quite anoying on a windows system,
> that you always have to choose manually the application, when you open a
> style file.

You can associate any program to open up files without extensions. google
it. .txt would be more beginner friendly though.

>
>
> Gruss
> Torsten
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