[Talk-us-massachusetts] well, so much for the Lynn Woods effort

[Greg Troxel]

[I have taken a break from this subject and not read the whole thread.]

"Brian M. Sperlongano" <zelonewolf at gmail.com> writes:

> In short:
> - Boundaries are tagged as boundaries
> - Land cover is tagged as land cover for the actual parts of land covered
> by the type of land cover
> - Multipolygon relations are composed of inner and outer ways, and no other
> types

I would add:

  As an aside, boundaries are sometimes true boundaries (e.g. town) and
  sometimes the word boundary=protected_area, which while using the word
  boundary is really tagging a property of the enclosed are.  This is a
  major cause of semantic mess within OSM and contributes to
  representing boundary=protected_area as a line around rather than a
  fill.  But in some sense, the boundary of an area and the area are the
  saem thing.

  A) Some properties are actually aligned.  Generally the following are
  coincident:
    - parcel boundary
    - boundary=protected_area (and landuse=conservation, often both
      true, but there are cases when one is true but not the other)
    - leisure=nature_reserve and name
    - ownership and access tags
  so it makes sense for them to be on the same object.

  B) land cover is never properly aligned with parcel boundary.  It
  might be, in some very rare case, true at one minute, but nature
  happens and landcover changes.  People will want to change and extend
  landcover objects as things change.  So therefore it is never ok to
  have landcover tags on an object described in class A.  An exception
  would be a natural=water object where the law says that the property
  boundary is the waterline (e.g. great ponds), so a pond shoreline and
  an adjacent type A landuse-flavor object could share a way.

Probably we should have a validator that flags landuse and landcover
being on the same object as an error, and better yet, also one that
flags landcover lining up with parcel boundaries as an error.


In short: never add landcover tags to landuse-type objects.
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