If you look at the Stack response from David he had suggested breaking the geohash up into pieces and then using a prefix for refining precision. I hadn't imagined limiting this to a particular area, just limiting it based on the prefix (which would be based on users zoom level or something) allowing the information to become more precise as the user zoomed in. That seemed a very reasonable approach to the problem.
On Mon, Jun 11, 2012 at 10:55 AM, Tanguy Moal <tanguy.m...@gmail.com> wrote: > 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 >>
