Yeah I'll have to play to see how useful it is, I really don't know at this point.
On another note we already using some binning like is described in teh wiki you sent, specifically http://code.google.com/p/javageomodel/ for other purposes. Not sure if that could be used or not, guess I'd have to think on it harder. On Mon, Jun 11, 2012 at 12:04 PM, Tanguy Moal <tanguy.m...@gmail.com> wrote: > Yes it looks interesting and is not too difficult to do. > However, the length of the geohashes gives you very little control on the > size of the regions to colorize. Quoting wikipedia : > geohash length > > > km error1 > > > > ±25002 > > > > ±6303 > > > > ±784 > > > ±205 > > > ±2.46 > > > > ±0.617 > > > > ±0.0768 > > > > ±0.019 > This is interesting also : http://wiki.openstreetmap.org/wiki/QuadTiles > But it does what you're looking for, somehow :) > > -- > Tanguy > > > 2012/6/11 Jamie Johnson <jej2...@gmail.com> > >> 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 >> >> >>
