[Imports] [OSM-Talk-ZA] Cleaning up an old import

[Gerhardus Geldenhuis]

Hi
I would suggest downloading the section in JOSM if you don't already use
it. You can then very easily apply a filter and then select all the objects
and apply/change a preset where required. I would also suggested contacting
the contributor privately first before mailing to public forums. There
might have been a good reason for the classification and other issues you
mentioned.

Regards


On 10 February 2013 09:05, David Schneider <d.schneider at tradermail.info>wrote:

> Hi List!
>
> I searched an address in the eastern parts of Cape Town, and I was
> suprised that nomatim didn't report it as residential. I checked the
> data, and found that vast parts of Cape Town's residential areas are
> made up from unclassified roads instead of residential!
> From the metadata, this seems to be the result of an import some
> years ago.
>
> I feel this should be fixed. I don't know if this can be done auto-
> matically, or a manual community effort is required. My proposal would
> be to select "user=Firefishy  maxspeed=60 highway=unclassified" in JOSM
> and change all to residential. Now, a few roads that should be
> unclassified will be residential, but the ratio seems to be 99% wrong
> now vs. 1% wrong after this change. Of course, roads that have been
> touched since the import will missed by this, but there will be an
> improvement for sure.
>
> Another thing that I noticed is that the roads are massively over-noded.
> http://www.openstreetmap.org/browse/way/32216567 demonstrates both. It
> should be residential, and if you compare to aerial images, the straight
> section is represented with 6 nodes, 3 of them within 5m. I presume this
> comes from calculating the centerline of a full shape, as the road widens
> towards the east, where the many nodes are.
> (I would map that road with 3 nodes, with the two on the eastern sides
> interfacing between the NW-SE road, going away at 90° from there. I.e.
> making a slight right turn when going east. The data is just the opposite,
> going to the left, which gives an odd angle that is not there in reality
> when you come from the south and turn east.)
>
> I downloaded a section of Cape Town, exported to GPX and used gpsbabel
> to apply the Douglas-Pecker algorithm with 1m max deviation. The number
> of nodes went down to less than half! So maybe removing some excess nodes
> could be performed during any update.
>
> Best,
> David
>
>
>
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>


-- 
Gerhardus Geldenhuis
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