There is definitely something interesting to do around geohashes. I'm wondering how one could map the N by N tiles requested tiles to a range of geohashes. (Where the gap would be a function of N). What I try to mean is that I don't know if a bijective function exist between tiles and geohash ranges. I don't even know if a contiguous range of geohashes ends up in a squared box.
Because if you can find such a function, then you could probably solve the issue by asking facet ranges on a geohash field to solr. I don't if that helps but the topic is very interesting to me... Please share your findings, if any :-) -- Tanguy 2012/6/11 Dmitry Kan <dmitry....@gmail.com> > so it sounds to me, that the geohash is just a hash representation of lat, > lon coordinates for an easier referencing (see e.g. > http://en.wikipedia.org/wiki/Geohash). > I would probably start with something easier, having bbox lat,lon > coordinate pairs of top left corner (or in some coordinate systems, it is > down left corner), break each bbox into cells of size w/N, h/N (and > probably, that's equal numbers). Then you can loop over the cells and > compute your facet counts with bbox of a cell. You could then evolve this > to geohashes, if you want, but at least you would know where to start. > > -- Dmitry > > On Mon, Jun 11, 2012 at 4:48 PM, Jamie Johnson <jej2...@gmail.com> wrote: > > > That is certainly an option but the collecting of the heat map data is > > really the question. > > > > I saw this > > > > > > > http://stackoverflow.com/questions/8798711/solr-using-facets-to-sum-documents-based-on-variable-precision-geohashes > > > > but don't have a really good understanding of how this would be > > accomplished. I need to get a more firm understanding of geohashes as > > my understanding is extremely lacking at this point. > > > > On Mon, Jun 11, 2012 at 8:55 AM, Stefan Matheis > > <matheis.ste...@googlemail.com> wrote: > > > I'm not entirely sure, that it has to be that complicated .. what about > > using for example http://www.patrick-wied.at/static/heatmapjs/ ? You > > could collect all the geo-related data and do the (heat)map stuff on the > > client. > > > > > > > > > > > > On Sunday, June 10, 2012 at 7:49 PM, Jamie Johnson wrote: > > > > > >> I had a request from a customer which to this point I have not seen > > >> much similar so I figured I'd pose the question here. I've been asked > > >> if it was possible to build a heat map from the results of a query. I > > >> can imagine a process to do this through some post processing, but > > >> that sounds very expensive for large/distributed indices so I was > > >> wondering if with all of the new geospatial support that is being > > >> added to lucene/solr there was a way to do geospatial faceting. What > > >> I am imagining is bounding box being defined and that box being broken > > >> into an N by N matrix, each of which would return counts so a heat map > > >> could be constructed. Any other thoughts on this would be greatly > > >> appreciated, right now I am really just fishing for some ideas. > > > > > > > > > > > > > > > -- > Regards, > > Dmitry Kan >
