[google-appengine] Re: Problems with Geohash / Inaccuracy / ow to deal with this ?

[Pierre VANNIER]

Mark a écrit : Hi Pierre, take a look at the following link: http://github.com/davetroy/geohash-js/tree/master/README Creating an arbitrary bounding box may overlap Geohash 'fault lines' which can be very non-contiguous in terms of sorting. On Sep 4, 4:35 pm, Pierre <[EMAIL PROTECTED]> wrote: Thanks for your reply Adam. That's true "doesn't imply there are no poi outside of the bbox which don't also satisfy this.". But, then, it means this heuristic : "SW Geohash / NE geohash then GQL for points > to SW and < to NE" will retrieve points also located outside bounding box ... What is it then ? are we looking for a Minimum bounding rectangle ? But this program returns also outside points... where is the magic ? Why does everybody spring around geohash then ? This heuristic returns an exact set of points located in a bounding box as you could say a car cost between 100 and 10.000 dollars...No precision at all. So, I thought I missunderstood how to use geohash but it seems it's not the case. Strange. Is there any geohash master over there to explain if yes or no it is possible to be precise for points located in a bounding box with geohash and gae ? Regards, Pierre On 4 sep, 23:02, Adam <[EMAIL PROTECTED]> wrote: No idea really. Though assuming sw < poi < ne for all poi in the bbox, doesn't imply there are no poi outside of the bbox which don't also satisfy this. The implications of this: sw = geohash.Geohash('speq0uw18pb50') ne = geohash.Geohash('spvg2gn5bpb08') bb = sw + ne bb.bbox()   (0.0, 39.375, 11.25, 45.0) are interesting. A Thanks mark for this link. To conclude, correct me if I'm wrong : - Geohash is good to find a given Poi's neighborhood - Geohash cannot be precise enough to retrieve points in a given Box even if this box is geohash coded My primary goal was to load some Poi on google map. As per performance issues, I'd have liked to load solely Pois located in the visible area of the screen and fetch new Poi as the user is draging the map. This seems to be a bad idea and I'm going to look for another method. Thanks Folks for your help. Pierre --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---