[mkgmap-dev] is_in filter

Mon Feb 6 19:55:17 GMT 2017

Hi Carlos,

okay, I thought about this for a while. We need quite a lot of new code for this, so I think
the user interface should be as flexible as possible.
If we want to support a style function like is_in(<exp>)
where <exp> can be something like
landuse=residential
or more complex stuff like
landuse=forest | natural=wood
In short, I think it should support more or less all Tag_tests including regular expressions
and combined expressions. A complete style rule could look like this:
building=* & !is_in(landuse=residential | landuse=retail)   [0x13 resolution 24]
Those Tag_tests are used to filter the enclosing areas (closed ways, multipolygon-relations).

I have no idea how to code the part that parses the style file.
Is someone volunteering to code these changes?
I think about a new class IsInFunction in package uk.me.parabola.mkgmap.osmstyle.function
which would call an eval(element) method for each enclosing element. The eval method
should return true / false.

I'd like to code the needed methods to find the enclosing elements in an efficient way.

If nobody finds a way to code the above style changes
I can code a style function with a much simpler syntax like this:
is_in_<key><val>()
e.g.
is_in_landuse_residential()
or
is_in_natural_wood()
The name of the function gives the test:
The enclosing element must have a key <key> with the value <val>

Complex tests like regular expressions would not work with this.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Carlos Dávila <cdavilam at orangecorreo.es>
Gesendet: Samstag, 4. Februar 2017 16:37:11
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] is_in filter

Yes, I think that would work.
I forgot to mention another use case. highway>residential which lies
inside residential areas. They have typically maxspeed lower than
outside residential areas, but are not correctly tagged in many cases.
Proposed filter could be used to lower maxspeed for those ways.

El 04/02/17 a las 16:18, Gerd Petermann escribió:
> Hi Carlos,
>
> I see a performance problem if mkgmap has to evaluate that for each element.
> I think it would be better to have a special tag like mkgmap:remove-if-in=<type>
> which would tell mkgmap to find out if the object lies (completely) within a polygon
> that has the given type. This can happen after processing all polygon elements.
> The polygons with the given type(s) could be placed in a spatial index if performance impact
> is too heavy.
> Do you think that would work as well?
>
> Gerd
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Carlos Dávila <cdavilam at orangecorreo.es>
> Gesendet: Samstag, 4. Februar 2017 16:06:20
> An: Development list for mkgmap
> Betreff: [mkgmap-dev] is_in filter
>
> One matter that has been discussed several times on this list is the
> need to remove buildings. While removing buildings is becoming
> absolutely necessary in many cities, due to massive building imports, it
> may be quite convenient to keep them at rural or low densely populated
> areas. Would it be possible to have a filter to know if a building is
> inside/outside an area tagged landuse=residential, so that a different
> rendering may be applied. Ideally area size could be also evaluated.
> Perhaps some logic currently existing in mkgmap, used to assign
> addresses from bounds, could be reused.

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