[gdal-dev] ArcGIS RestAPI JSON Polygons

[Jeremy Palmer]

I'm querying an ArcGIS service obtain polygon data, however the service seems to define Island multi-polygons objects as single polygons with multiple exterior rings. This creates invalid OGC geometries and is causing processing problems in my workflow.

He's the service and a validation test showing the polygon is not valid:

ogrinfo -dialect sqlite -sql "SELECT TA2013_V1_00_NAME, ST_IsValid(GEOMETRY) FROM OGRGeoJSON" http://maps.stats.govt.nz/wss/service/arcgis1/guest/Boundaries/2013_Geographies/MapServer/9/query?f=json&objectIds=36&returnGeometry=true&outSR=4167

GEOS warning: Hole lies outside shell at or near point 174.78189611685229 -41.077770200471164

Layer name: SELECT
Geometry: None
Feature Count: 1
Layer SRS WKT:
(unknown)
TA2013_V1_00_NAME: String (0.0)
ST_IsValid(GEOMETRY): Integer (0.0)
OGRFeature(SELECT):0
  TA2013_V1_00_NAME (String) = Porirua City
  ST_IsValid(GEOMETRY) (Integer) = 0

Is this a bug in the data from the service, or just the way the Esri defines geometry objects (and therefor an OGR bug)? I can't see a definition for multi-polygons in Esri API docs:

http://resources.arcgis.com/en/help/arcgis-rest-api/index.html#//02r3000000n1000000

Cheers,

Jeremy Palmer
LINZ Data Service Manager
Landonline & Geospatial Services

E  jpalmer at linz.govt.nz | DDI +64 4 498 3537 | M +64 27 2747 862

Wellington Office, Level 7, Radio New Zealand House, 155 The Terrace
PO Box 5501, Wellington 6145, New Zealand | T 04 460 0110
W  www.linz.govt.nz<http://www.linz.govt.nz/> | www.landonline.govt.nz<http://www.landonline.govt.nz/> | data.linz.govt.nz<http://www.data.linz.govt.nz/>
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