[gdal-dev] ArcGIS RestAPI JSON Polygons

[Mateusz Łoskot]

On 23 June 2014 19:46, Jeremy Palmer <JPalmer at linz.govt.nz> wrote:
> http://resources.arcgis.com/en/help/arcgis-rest-api/index.html#//02r3000000n1000000
>>
>> Can you?
>> There is no geometry of multipolygon specified.
>> AFAIU, for multipolygon ESRI REST produces a hybrid: a Polygon that
>> contains detached rings
>> (or rings not in other rings, so they are not holes) and that is
>> interpreted as multipolygon.
>>
>> Fun.
>
> The definition says polygons can have any number of rings, either exterior or interior. Exterior rings are oriented clockwise, while holes are oriented counter-clockwise.

It does not say anything about interpreting such a multi-exterior ring
as multipolygon, either, OGC or GeoJSON ones.
It is just a description of ESRI-specific JSON-encoded kind of polygon geometry.

> Maybe the OGR driver should be improved to check for this. If more than one exterior ring is found then an OGC multi-polygon geometry object should be returned. Could check the orientation via area or the http://en.wikipedia.org/wiki/Even%E2%80%93odd_rule

Might be. I just pointed out that OGR GeoJSON driver is dedicated to
GeoJSON specifically, not any JSON-encoded format of geometry.


Best regards,
-- 
Mateusz  Łoskot, http://mateusz.loskot.net