[GeoJSON] polygon orientation, trying number 2

Sean Gillies sean.gillies at gmail.com
Fri Jul 15 17:38:54 PDT 2016


Hi Anna,

Thanks for letting us know about this! I've updated the examples in our
GitHub repo and sent a patch along to the RFC Editor. When the GeoJSON
standard is published, the examples will have the correct orientation:
exterior rings that wind counter-clockwise and interior rings that wind
clockwise.

See https://github.com/geojson/draft-geojson/issues/231 for the specific
changes.

Yours,

On Thu, Jul 14, 2016 at 4:56 AM, Anna Eivazi <Anna.Eivazi at sharpershape.com>
wrote:

> Hello geojson-gurus,
>
>
>
> First of all, thank you for all your good work about geojson, we love to
> use it!;)
>
>
>
> I’ve got a question after trying to figure out which orientation to use
> for polygons.
>
>
>
> So I’ve read your latest specs:
>
> https://datatracker.ietf.org/doc/draft-ietf-geojson/?include_text=1
>
>
>
> Here it is said:
>
> Polygon rings MUST follow the right-hand rule for orientation
>
>       (counter-clockwise external rings, clockwise internal rings).
>
> (clear answer to my question, right?)
>
>
>
> But a bit upper in the same doc Polygon section:
>
>
>
> A.3.  Polygons
>
>
>
>    Coordinates of a Polygon are an array of LinearRing (see
>
>    Section 3.1.6) coordinate arrays.  The first element in the array
>
>    represents the exterior ring.  Any subsequent elements represent
>
>    interior rings (or holes).
>
>
>
>    No holes:
>
>
>
>      {
>
>          "type": "Polygon",
>
>          "coordinates": [
>
>              [
>
>                  [100.0, 0.0],
>
>                  [100.0, 1.0],
>
>                  [101.0, 1.0],
>
>                  [101.0, 0.0],
>
>                  [100.0, 0.0]
>
>              ]
>
>          ]
>
>      }
>
> That would mean clockwise orientation…?
>
>
>
> So, which one u are planning to use in future? So we will stick to it too!
>
>
>
> Thanks a lot!
>
>
>
> Best regards,
>
> Anna Eivazi
>
>
>
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>
>


-- 
Sean Gillies
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