[OSM-dev] proposal to kill areas

Lars Aronsson lars at aronsson.se
Sun Jul 23 00:57:17 BST 2006


Tommy Persson wrote:

> Since I try to do nice map of some area of Linköping I was 
> thinking about adding some parking lots, forrests, golf course, 
> green areas, etc.

Yes, but how do you get the data?  Do you walk the edge of the 
forest with your GPS receiver?  Or do you draw freehand from the 
satellite images? At the parking lot, do you walk its edges, or do 
you walk every lane and slot?  Or do you walk randomly over the 
surface to get a lot of (yellow) dots that mark the area?  Do you 
intend to mark both the edge of the forest and any roads (or 
bikepaths) that run through the forest?

At a few places, I have marked where a road crosses a border, and 
in the map I have drawn a little short line segment perpendicular 
to the road, made it a "way" of class="border" and the name of the 
two areas, e.g. name="Sweden - Norway".  But I have no idea how 
the border continues beyond the road.

As far as I can see, town squares and parking lots (and place de 
l'Étoile in Paris, the traffic circus around the Arc de triomphe) 
are just a kind of line segment that happens to extend in two 
dimensions.  There are no roads inside such objects, and they 
seldom extend beyond a few hundred metres.  I'm a little more 
doubtful about parks and forests, since they can contain other 
roads, parking lots, and squares.  In this, they are a lot more 
like "counties" and other generic container objects.  There is 
also no end to how large a forest can be.  Such large and generic 
containers could create enormous performance and complexity 
problems.


-- 
  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se




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