BarnesSurface is not what you want - it does a lot of interpolation that
doesn't sound as if it's required.
One way to do this is to do the aggregation on the PostGIS side. There's
various ways to do this:
- You can create a grid of cells of the desired shape and dimensions (e.g.
either square or hexagonal), spatially join this to the source data points,
and then aggregate by cell.
- A slicker and faster way is to compute the cell index of each point
mathematically (which avoids the need for the spatial join). For squares
this is fairly trivial, for hexagons it's harder. Then do the aggregation
as before. The cell geometry needs to be computed as well, but only for
display purposes.
It would also be nice to have this functionality run dynamically as a
GeoServer process running as a Rendering Transformation. This would be
similar to the existing PointStacker process, but would aggregate to cell
polygons and then return the cells as a feature collection.
On Wed, Feb 6, 2013 at 1:04 AM, Chris Haste <[email protected]> wrote:
> Hello list,****
>
> ** **
>
> I really haven’t a clue where to start with this so any pointers would be
> gratefully received.****
>
> ** **
>
> I have a global data set residing in a postgres/postgis database. The
> geographic spread of the data is random, some areas have a lot of points
> whereas others have quite sparse points. The data basically boils down to a
> location and an integer value between 0 and 4.****
>
> ** **
>
> I would like to represent this data as a series of fixed sized cells
> (shape not important but hexagonal would look nice!). If no data point
> resides within a cell I’d like to colour the cell purple. If more than one
> data point resides within a cell I’d like to colour it based on only the
> highest number amongst those points within the cell.****
>
> ** **
>
> I’d like the cells to completely cover (and probably be clipped by) by
> coastline data. The net effect I’m after would be the landmasses shown as a
> patchwork of coloured cells.****
>
> ** **
>
> I have tried playing around with a gs:BarnesSurface but I don’t see able
> to get the results I’m after with this method. Any ideas? ****
>
> ** **
>
> Thanks****
>
> ** **
>
> Chris****
>
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