On Tue, Feb 15, 2011 at 1:13 PM, bude <[email protected]> wrote:
>
> Hi,
>
> Can someone help me with SLD. I have problem to group elements when map is
> zoomed to small zoom and represent them.
>
> Just for example: Let say that we have N hospitals on some area. When zoom
> level is set to show wide range of area, I just want to draw hospitals
> cluster image with number of them (N). After zoom lvl is increased I want
> to
> show every single hospital on the map.
> I suppose that I need to use aggregate functions in the SLD but there is no
> much doc explanation on this or examples.
>
>
The geometry transformations, available on the stable series (2.0 and 2.1),
can only alter a single geometry at a time.
Grouping requires taking many features and coming out with a single one,
it is a collection level operation.
On trunk we have the support to make this kind of operations (some examples
here:
http://geo-solutions.blogspot.com/2011/01/developers-corner-have-your-sld.html
,
they talk about raster/vector transformations but the mechanism is actually
generic).
To do what you want it should be possible to develop some sort of
aggregation process
that groups data on the fly (since it has to work in memory I guess it would
work only
with limited amounts of data).
Long story short, the tech is there, it should land on 2.1.x soon, but it's
pretty
new and doing it right might not be a trivial task. That said, it's
definitely possible.
Cheers
Andrea
-------------------------------------------------------
Ing. Andrea Aime
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