On 28/04/2013 15:21, Andrew wrote:
David Earl <david@...> writes:
In general, it shouldn't be necessary to
have a node and an area which
represent the same thing.
In this case the nodes and areas do not
represent the same thing. The areas are
the local government districts called
Leeds and Manchester but the nodes are
the settlements of Leeds excluding for
instance Morley and Manchester
including for instance Salford.
OK, City of Manchester and Greater Manchester aren't the same thing. But
there will usually be an administration that _is_ the place (i.e. the
boundary of the place follows the boundary of the adminstrative area),
even when there is a larger unitary authority encompassing more than one
such place. Place has little meaning otherwise - a town or civil parish
or whatever _is_ the place.
There is an argument that says 'place' is an informal concept that
should only be represented as a node, different from administrative
boundaries. This gets perilously close to mapping for the renderer
though ("I want a label HERE").
There's also a useful concept of the "urban envelope" where you want to
draw a grey splodge on a map to represent a built-up area. The various
urban landuses almost get this, but for a clean map you don't really
always want the small outliers or rural dwellings that might be marked
landuse=residential. Once could argue that place areas serve that need.
Whatever, I suspect it has been done in any and all combinations,
because informal place predates the more formal (or formerly
inaccessible to us) admin boundaries.
David
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