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 <[email protected]> wrote: ----- To: Graham Jones <[email protected]> From: Frans Thamura <[email protected]> Date: 21/01/2012 10:16AM Cc: Nick Whitelegg <[email protected]>, OSM-talk Openstreetmap <[email protected]> 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 <[email protected]> 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. >
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