[Geojson] GeometryCollection not treated as a Geometry type

[Stephen Battey]

If MultiPoint, MultiLineString and MultiPolygon objects provide
compatibility with OGC SF then they are not redundant.
My thoughts were that a MultiPoint, say, has better type safety than a
GeometryCollection that contains multiple Points. That would explain why
you might use one or the other but it doesn't explain why a Geometry
object with MultiPoints is a single geometry while a GeometryCollection
with multiple points is not. Should there be a distinction?

Maybe I'm mis-reading the spec. Maybe there isn't a distinction between
single geometry and geometry collections.
Are geometry collections allowed inside geometry collections - or is the
geometries array restricted to single geometry objects?

Steve



> -----Original Message-----
> From: Martin Daly [mailto:Martin.Daly at cadcorp.com] 
> Sent: 08 October 2007 12:17
> To: Stephen Battey; Christopher Schmidt; geojson at lists.geojson.org
> Subject: RE: [Geojson] GeometryCollection not treated as a 
> Geometry type
> 
> 
> > Well, this got me wondering ... if we can define a geometry using a
> > geometry collection (i.e. multiple geometries), are MultiPoint,
> > MultiLineString and MultiPolygon redundant?
> 
> That is an entirely arbitrary cut-off point.
> 
> One could just as easily argue that, because GeometryCollection could
> contain a single Geometry, that Point, LineString and Polygon are also
> redundant.  It has also been argued, a month or so ago
> (http://lists.geojson.org/pipermail/geojson-geojson.org/2007-S
eptember/0
00206.html) that Point, LineString and Polygon are redundant because a
single-Geometry MultiPoint, MultiLineString or MultiPolygon is the same
thing, thus ending up with a different, but also arbitrary, subset.

For me, either we have all types (+1, and +compatibility with OGC SF),
or we have one type (-1).

M
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