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

Tue Jul 7 17:15:02 BST 2009

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.

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.

Gruss
Torsten