[OSM-newbies] How to draw land-use areas
david.fawcett at gmail.com
Tue Apr 17 14:20:27 BST 2012
+1 well said.
On Mon, Apr 16, 2012 at 8:50 PM, Alan Mintz <Alan_Mintz+OSM at earthlink.net>wrote:
> At 2012-04-16 11:46, Sam Kuper wrote:
> On 16 April 2012 02:15, Serge Wroclawski <emacsen at gmail.com> wrote: On
> Sun, Apr 15, 2012 at 8:57 PM, James Ewen <ve6srv at gmail.com> wrote:
> > My personal feeling is that if you're going to map landuse to the >
> physical edge of the road, then you should create the road as a > polygon
> to show the edge of the road sharing the edge of the landuse.
> Roads as polygons is really poorly supported in OSM, and by poorly supported,
> I mean that for the most part, they're not at all, and should be avoided.
> While you might be able to render them, the renderer already has support
> for rendering road size based on road type- using areas will mess that
> up. In addition, AFAIK, none of the routing engines in OSM support roads
> as areas, so using them would be a problem for both renderers and routers.
> In my view, OSM's lack of support for roads (which areÂ polygons, not
> lines) as polygons is a bug in dire need of fixing.
> Technically, everything is a polygon, since a line cannot exist in the
> physical world. So, proper tools (including OSM) either add a width
> property to them or assume a width based on other criteria (like road
> class). This works fine for most purposes, and avoids the performance
> penalties of unnecessary detail.
> Map roads as polygons, I say! And any of us finds that the tools don't
> facilitate that, then (s)he should stop tagging for the moment and turn
> her/his attention to improving the tools.
> If we get this right, then eventually we'll be able to use OSM to look up
> the dimensions of roads, pavements, traffic islands, central reservations,
> etc, which has the potential to be very useful in support of open planning.
> I disagree. Even professionals see no need for this. County road databases
> (all that I've seen) are all based on centerlines, with traffic classes,
> widths, etc. well-used for necessary traffic planning. The details of
> particular curb, lane, and island placements are all available in the
> various map books, which are often available online by links. This isn't
> because of lack of capability - all current tools have support for polygons
> - it's simply a matter of using the right feature for the job. There's no
> reason to overload one map layer with all that detail that is of no
> importance to the vast majority of consumers.
> In the OSM world, I believe it's not presumptive to say that the vast
> majority of mappers are unwilling to go out there with a survey crew and
> measure the type of details your talking about, nor to (probably manually)
> import them from engineering drawings, nor to want to support the
> performance penalty caused by having to render all that detail, for no real
> benefit to them or anyone they can think of.
> ** --
> Alan Mintz <Alan_Mintz+OSM at Earthlink.net>
> newbies mailing list
> newbies at openstreetmap.org
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