On Thu, Mar 21, 2013 at 11:20 AM, Andrea Aime
<andrea.a...@geo-solutions.it>wrote:
> On Thu, Mar 21, 2013 at 7:18 PM, Martin Davis <mtncl...@gmail.com> wrote:
> > Agreed - all good points.
> >
> > If GFI did access the RT output, I was thinking that it would be
> possible to
> > add a mode to the PointStacker RT where it returned all the original
> > features, but with a point coordinate set to the location of the computed
> > cluster point. Then this mode could be enabled in the GFI call, thus
> > retrieving all the original features. But with the current disconnect
> > between GFI and RT, this won't work.
>
> You'd get a MultiPoint, but with just the coordinates, you would not have
> their attributes. That's why I was suggesting to get a list of feature
> ids instead.
>
I meant that the new mode would compute a cluster point for groups of
features, but then return *each original feature* but having as geometry
the computed cluster point. So the GFI spatial filter would select all the
features in the cluster, and would get back full attribution for each one
of them. (PointStacker reads all the features in the map window before
outputting them, so it can choose to output any mixture of attributes and
spatial required).
> A more compact solution would be to issue a polygon with the convex hull
> of all the points used in the cluster, which could also be used in
> GetFeature
> to retrieve all the features and their attributes
>
Interesting idea. The clustering is based on a square grid, so it could
just return the grid cell outline. But what query would retrieve this
polygon? The RT output is only available to the renderer, right? So
doesn't this mean that WPS would have to be used to call the PointStacker
process directly?
But I just remembered a tricky issue about calling PointStacker via WPS:
the grid resolution is determined from the map window dimensions. These
are available inside the rendering pipeline, but won't be in a WPS call.
Probably not impossible to detemine them on the client side, but that
stars to get a bit ugly. So that brings us back to the idea that it would
be nice to be able to run a GFI against the RT output.
Martin
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