[Talk-us-massachusetts] Is there a MA policy on mapping polygons with shared ways?

[Greg Troxel]

"Wayne Emerson, Jr. via Talk-us-massachusetts"
<talk-us-massachusetts at openstreetmap.org> writes:

> In this weeks OSM weekly roundup http://weeklyosm.eu/archives/12467
> there is this quote, "Adam Franco created two videos about working
> with multipolygons using JOSM. Thefirst one
> <https://www.openstreetmap.org/user/Adam%20Franco/diary/390981>is
> about creating multipolygons for adjoining areas with shared
> ways. Please note that this type of mapping is being discouraged in
> many parts of the world."
>
> I wasn't sure which type of mapping was being discouraged. So for
> example if we have a swamp bordering a salt marsh, which is bordering
> a tidal flat, should we have 3 polygons with overlapping lines &
> shared nodes, or do we make them into multipolygon relations?

I am not really following.

Sometimes, people use ways that make up a road as landuse boundaries,
and this seems generally agreed to be bad.

If you mean there are a bunch of ways, and then there are adjacent
polygons that each contain the boundary way, such that:

  - the boundary way really is the boundary between swamp and marsh

  - the boundary way does not have tags

  - the two polygons have tags

then to me that seems not problematic.

I don't see how you'd use a multipolygon to represent this; that would
make sense when there were holes, or multiple areas that are logically
the same.  Even still, I could see a multipolygon of one type using ways
and another multipolygon also using the ways.  But this doesn't seem to
change the shared way notion.

When I map landuse, I tend to not share ways, but instead to have ways
on each parcel group just inside.  But I don't think that's better; it's
just what I know how to cope with easily in JOSM.

Hope this helps; not really sure at all!