[talk-ph] to share or not to share nodes?

Eugene Alvin Villar seav80 at gmail.com
Tue Apr 27 16:06:57 BST 2010

Personally, I am more bothered with overlapping ways than with shared nodes.

Nodes should be shared if the two ways sharing that node have an intrinsic
positional relationship on that node. If you use two different nodes with
the same coordinates, then you risk having the duplicated node problem.

As for admin boundaries sharing nodes, sometimes that is the only clean way
to signify the relationship of an admin boundary with surrounding landuses.
Case in point is the eastern boundary of Barangay Ayala Alabang in
Muntinlupa <http://osm.org/go/4zgXRLjkm->. This border is exactly the
eastern perimeter of Ayala Alabang Village. The landuse covering Ayala
Alabang Village shares almost all of its nodes with the ways that make up
Brgy. Ayala Alabang. I actually am thinking of breaking up the Ayala Alabang
Village landuse polygon into parts, delete the redundant ways and create a
multipolygon relation reusing the admin boundary ways so that there are no
more overlapping ways.

On Tue, Apr 27, 2010 at 5:33 PM, maning sambale
<emmanuel.sambale at gmail.com>wrote:

> Hi,
> I'm posting this inquiry to gather best practices when editing nodes
> and ways.  Basically, OSM data are composed of two data primitives:
> nodes (points, vertices) and ways (lines and polygons).  Relations are
> special type of ways and nodes.  The data model allows for sharing
> nodes/ways with different tags.  For example, a node can be part of a
> highway, traffic_signals can be added to node which is part of a
> highway way.
> However, in many cases it is good editing practice to minimize node
> sharing.  Partly for ease of editing and partly to avoid routing
> errors (especially for highway ways).  Here's a list of editing
> practices I will use from hereon in order to avoid node sharing
> problems mentioned above.  Please add or delete anything in the list.
> 1. Highways should not share nodes with other non-highway related ways
> (such as administrative boundaries, landuse, building outlines)
> 2. Nodes for adjacent landuse types can share nodes.
> 3. Administrative boundaries should be in relations not as shared
> nodes/ways.
> 4. Natural and landuse ways can share nodes.  For example,
> natural=water (for lakes) can share nodes with landuse=farm.
> 5.  Admin boundaries should not share nodes with landuse.  Landuse
> change more often than admin boundaries.
> 6.  add more here ...
> --
> cheers,
> maning
> ------------------------------------------------------
> "Freedom is still the most radical idea of all" -N.Branden
> wiki: http://esambale.wikispaces.com/
> blog: http://epsg4253.wordpress.com/
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