[Geojson] featurecollection in featurecollection

[Jeremy Cothran]

I read through the earlier thread about this at
http://lists.geojson.org/htdig.cgi/geojson-geojson.org/2008-October/000464.html

and was not sure as to its conclusion - whether GeoJSON supports nested
FeatureCollections or prohibits them.

The application-specific issue that we are working with and trying to
resolve is towards sharing recent ocean observations as GeoJSON , for
example we have ocean buoy platforms which contain a collection of sensors
with each sensor containing a collection of associated observations.

I've taken a shot at describing this as a GeoJSON microschema (ObsJSON) at

http://code.google.com/p/xenia/wiki/ObsJSON#Simple_schema_version_2

where each GeoJSON file contains only one platforms recent observations and
each feature models a sensor and its associated observations

{
    "type": "FeatureCollection",
    "schemaRef": "ioos blessed schema name reference(s)",
    "dictionaryRef": "ioos blessed obstype uom dictionary reference(s)",
    "dictionaryURL":
"http://nautilus.baruch.sc.edu/obsjson/secoora_dictionary.json",
    "platformId": "urn:x-noaa:def:station:noaa.nws.ndbc::41012",
    "metadataURL": "link to further operator/platform metadata/links
as XML/JSON",
    "operatorName": "ndbc",
    "operatorURL": "http://www.ndbc.noaa.gov/",
    "platformName": "41012",
    "platformURL": "http://www.ndbc.noaa.gov/station_page.php?station=41012",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "type": "MultiPoint",
                "coordinates":
[[-80.55,30.04,3],[-79.00,31.00,3],[-78.00,32.00,3]]
            },
            "properties": {
                "sensorId": "link to further sensor metadata/links as XML/JSON",
                "obsType": "air_temperature",
                "uomType": "celsius",
                "time":
["2009-03-31T10:50:00Z","2009-03-31T11:50:00Z","2009-03-31T12:50:00Z"],
                "value": ["22.0","23.0","24.0"]
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "MultiPoint",
                "coordinates":
[[-80.55,30.04,-1],[-79.00,31.00,-1],[-78.00,32.00,-1]]
            },
            "properties": {
                "sensorId": "link to further sensor metadata/links as XML/JSON",
                "obsType": "water_temperature",
                "uomType": "celsius",
                "time":
["2009-03-31T10:50:00Z","2009-03-31T11:50:00Z","2009-03-31T12:50:00Z"],
                "value": ["17.0","18.0","19.0"]
            }
        }
    ]
}


Not sure if the above schema is kosher in regards to GeoJSON property
listings containing time/value lists which might be cross-associated with
location lists or potential nesting of properties(contact lists with similar
contact properties) at the featurecollection metadata level.

The follow-up question that I've had is that if someone makes a bounding-box
request for several platforms, could the above type featurecollection
results be further nested within a featurecollection of multiple platforms.

Thanks
Jeremy Cothran
Software Developer
http://groups.google.com/group/xeniavm
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