[Talk-ca] [Imports] canvec-to-osm 0.9.6 now available

[Andy Allan]

On Sat, Nov 7, 2009 at 3:50 PM, Ian Dees <ian.dees at gmail.com> wrote:

> This is the desired effect. Technically there should be one multipolygon
> defining the waterway (or lake) and another multipolygon for the wooded area
> (with separate ways? or maybe the wooded area's outer way should be the
> lake's inner way?).

If they are non-overlapping and abutting, they two multipolygons
should share the same way. Or, more helpfully, if a mapper will always
want to adjust both at the same time, they should be the same way. For
example, if there is an inner way of a lake multipolygon, and another
way representing the island (e.g. with its name) then there should
only be one way. There can't be a gap between the edge of the lake and
the start of the island; if there extra nodes need adding to better
define the edge of the lake then it needs changing on the island too.

Forest polygons on islands might be more tricky, since if there are
significant areas of either beach or some other non-trees then a
mapper might want to make the forest smaller than the hole in the
polygon at some point in the future. I've yet to see a sufficiently
high quality import where the GIS department works to the same kind of
accuracy that we do!

> Keep in mind that removing duplicate nodes/ways in all cases is bad ... in
> some cases there actually are two features at the exact same point.

If those features, in the real world, can be moved independently, then
they should be two ways. If fixing the shape of one necessitates
making the same changes to the other, the nodes/ways should not be
duplicates of each other.

Cheers,
Andy