[OSM-talk] geojson

Nick Whitelegg Nick.Whitelegg at solent.ac.uk
Sat Jan 21 14:16:42 GMT 2012


Hi Frans/Graham,

Just to clarify this: on my site, the client does indeed only request data for the bounding box currently being displayed, see
http://www.free-map.org.uk/svn/freemap/fmap2012/ws/features.php.

The features.php script expects a bbox (comma-separated west,south,east,north bounding box) parameter.

All the freemap code is available at

http://www.free-map.org.uk/svn/freemap/.

I haven't actually worked on simplifying the feed at low zoom levels just yet, though my approach would be to filter based on feature type (e.g. only cities and large towns).

Nick

-----Frans Thamura <frans at meruvian.org> wrote: -----
To: Graham Jones <grahamjones139 at gmail.com>
From: Frans Thamura <frans at meruvian.org>
Date: 21/01/2012 10:16AM
Cc: Nick Whitelegg <Nick.Whitelegg at solent.ac.uk>, OSM-talk Openstreetmap <talk at openstreetmap.org>
Subject: Re: [OSM-talk] geojson

i post another question related to this, in the OSM API question

we will see, :) we will use your JSON model :)

and we can see what issue will raise up, and we have started the
threada about this scalability. that will become my homework to solve
that, when it happen

F


On Sat, Jan 21, 2012 at 5:08 PM, Graham Jones <grahamjones139 at gmail.com> wrote:
> Hi Frans,
> I haven't checked Nick's code, but I think that it works by the client
> requesting data for the specific area that is being displayed on the map.
> The BrewMap code just uses a single data file to cover the entire area (in
> this case the uk), so even if you zoom in very close, it still uses data for
> the whole uk.   This is fine if you only have a few hundred data points, but
> will become very slow if you have tens of thousands.
>
> Now for low zoom levels (large displayed areas) this amounts to the same
> thing, so there would be no benefit, unless you do some filtering on the
> server side to simplify the data (eg group POIs if they are going to be
> plotted on top of each other).   I have not done this yet, but Nick, and the
> folks working on KothicJS are likely to have thought about it and may have
> solutions, which is why I think it is worth investigating how they do it.
>
> Whether it is worth putting effort into simplifying the data on the server
> depends on how much data you are dealing with.
>
> Regards
>
> Graham.
>
> --
> Graham Jones
> Hartlepool, UK.
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk/attachments/20120121/7562bb15/attachment.html>


More information about the talk mailing list