[mkgmap-dev] Multipolygones and tags in outer line

Tue Feb 22 16:47:22 GMT 2011

Am 22.02.2011 16:55, schrieb Torsten Leistikow:

>> relation: type=multipolygon
>> outerway: landuse=forest (example)
>> innerway: no-tags (or tags for inner area).
>>
>> The forest is of course only the area between inner and outer.

> This is one of the accepted taggings for a multipolygon.
> 
> The other possibility (for the same example) is:
> 
> relation: type=multipolygon
>           landuse=forest (example)
> outerway: no-tags (or tags for whole area)
> innerway: no-tags (or tags for inner area).

the scope for the outerway-tags is depending on the existence
of tags on the relation (beside of type=mp) ?

I can't believ this.

Wiki:

The intended use of multipolygons is this:

 * Tags describing the multipolygon (e.g., landuse=forest) should go on
the relation. The outer way(s) should be left untagged, unless they
describe something in their own right. For example, a forest could be
delineated by four roads, in which case the four ways would be tagged
with the highway tag, but could still be used as "outer" members of the
forest relation.

 * If you have one closed way making up the outer ring and it does not
describe something in its own right, you may also put these tags on the
outer ring and leave the relation untagged. If you have more than one
outer way (see "Advanced Multipolygons" below), then this does not make
sense. Therefore it is suggested (for consistency) to always put the
multipolygon tags on the relation.

Tagging

 * It is suggested to apply all tags which describe the area to the
   relation, and not to the ways. In many cases this may result in
   completely untagged ways.

 * Implementation for compatibility:
   o Drawing style is taken from the tagging of the relation itself.
   o If relation is not tagged, the drawing style of outer ways is used.
   o If the outer styles mismatch or no style is found it is considered
     an error.
   o Inner tagging leads to inner drawing. If inner tagging style
     equals outer style (an old method) the inner style should be
     handled as empty.

Chris