I like the approach of using a new kind of coverage reader, the limitation is of course providing a suitable grid size (even though as an actual coverage your mathematical surface is not limited to a grid).
-- Jody Garnett On 6 April 2016 at 13:02, Justin Deoliveira <[email protected]> wrote: > Hi folks, > > I’m working on a project to expose Solr’s heatmap capability through > GeoServer. You can find details about Solr heatmaps here: > > https://cwiki.apache.org/confluence/display/solr/Spatial+Search (search > for “Heatmap Faceting”. > > But the gist of it is this: If you have a spatial field that uses the > recursive prefix tree type (ie. geohash) for indexing then it’s easy using > Solr’s facetting infrastructure to generate a heatmap grid. What you get > back from Solr is a 2D array representing the geohash grid, where each > value is a count of documents that intersect that grid cell. Applying some > symbolization you can get something that looks like this: > > > https://raw.githubusercontent.com/voyagersearch/leaflet-solr-heatmap/master/sample.png > > The above screen shot comes from a leaflet plugin that visualizes the > heatmap directly in the browser. I would like to add a similar looking > visualization for GeoTools/GeoServer. > > My first thought was to expose this as a new type of coverage reader, > since the data is simple grid it falls into the model quite easily. The > major benefit of this approach is that becomes trivial to configure in > GeoServer and easy to style using all of the existing raster symbology > support. I’m interested to hear if others think this is a good approach. > > If that sounds good my plan was to add this to the existing solr module. > It won’t add any new dependencies aside from a dependency on the coverage > module. > > @Andrea: you’re listed as the module maintainer… although if I recall > correctly we agreed to co-maintain the module? > > I have a prototype working so if that all sounds good I’ll push up a > branch for folks to look at. One thing I am particular eager to get some > feed back on is how to best achieve the blur affect that makes heatmaps > look “ > pretty”. At the moment what I have done is baked in a parameter to the > coverage format that specifies a blur radius and then when reading the > coverage I run it through the Convolve operation to achieve the desired > affect. It would be ideal if this could be done at symbolization time. I’m > wondering if we currently have any way to define a blur or some similar > effect at rendering time with sld? Would a rendering transform work? > > Thanks folks. > > -Justin > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > GeoTools-Devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/geotools-devel > >
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