[GeoJSON] GeoJSON in OpenLayers
sgillies at frii.com
Mon Mar 26 07:53:41 PDT 2007
Tim Schaub wrote:
> I've put together a GeoJSON reader/writer for OpenLayers. You can
> digitize some features and see the resulting GeoJSON (my own flavor) in
> this example:
> I'm not going to do anything with the reader until there is some
> agreement on the data structure. Also, I think this is understood, but
> I would suggest that any service that accepts something like
> outputformat=json also takes a callback=somestring - where the result is
> (allowing the somestring to be anything, including "NameSpace.property =
> " or "myFunction").
> If you digitize some points, lines, and polygons, I think the data
> structure I've got in mind should be obvious. It looks something like:
> "features": array,
> "crs": string
> The features array is an array of features where each feature looks
> something like:
> "id": string,
> "type": string,
> "attributes: object,
> "data": array
> The id string is any string. The type string is one of "point",
> "multipoint", "linestring", "multilinestring", "polygon", or
> "multipolygon" (and I'm entirely open to CamelCase). The attributes
> object is any object and the data array depends on the type.
> For type point, the data array is an array of coordinates like:
> [number, number]
> For type multipoint, the data array is an array of points as described
> For type linestring, the data array is an array of points as described
> For type multilinestring, the data array is an array of linestrings as
> described above.
> For type polygon, the data array is an array of linestrings as described
> above - and the client assumes that those linestrings will be linear
> rings. The first item in the array is the exterior ring and any
> subsequent items are interior rings.
> For type multipolygon, the data array is an array of polygons as
> described above.
> Finally, all features in the array have the same coordinate reference
> system, represented by the crs string.
> Though I haven't read too carefully, I think this captures the
> alternatives discussed here. Sean's Pleiades GeoJSON would use the
> attributes object for things like title, classname, and center. Same
> with things like AREA, PERIMETER, and DESCRIPTION from Chris.
> I'm happy to add this to the wiki somewhere if it looks sensible. Or,
> if it looks like gibberish, let me know.
> Related links -
> The GeoJSON reader/writer
> Which requires
> And if you want to make your own GeoJSON enabled OpenLayers application,
> point it to
I prefer "properties" (GML terminology) to "attributes" to avoid
explicit "geometry" attribute containing type and data. My $0.02.
I'm looking forward to trying out the new OpenLayers code soon.
More information about the GeoJSON