[OSM-dev] Trial clickable POI layer

David Earl david at frankieandshadow.com
Fri Sep 21 18:32:06 BST 2007

I think this has lots and lots of potential.

I think it is going to need separate "tiles" at each zoom level so the 
amount of data can be throttled (I assume this isn't going to the 
database for each overlay, but pre-generating them like the image tiles 
do, yes? If not, I think they should be - essentially they are companion 
data to the image tiles so can sit alongside the image tiles).

I suggest the "horizontal" text (names of POIs, place names etc) is also 
in these "tiles" (maybe a separate layer, I don't know what layers can 
hold, but if it is html, it can be both simultaneously).

I would also put _all_ the POIs (determined as useful for that zoom 
level) on one layer (two layers with text if necessary), but give them 
an HTML class; then have a control dialogue somewhere which allows the 
user to turn on and off the icons/text for particular classes of POI. So 
you can get churches or bus stops or whatever to dis/appear by ticking a 
check box. I think you could even include the actual icon in the style 
sheet rather than the data. This also has the potential for dynamic 
control over appearance: eg flash city names, make village names bigger 
and so on, simply by changing the style of the relevant class.


On 21/09/2007 18:03, Martijn van Oosterhout wrote:
> Hi,
> I've played with OL today and with some help from crschmidt I got the
> following working:
> http://kleptog.org/temp/test3.html
> It displays a mapnik map, with POIs over the top. Now, they basic
> functionality, but:
> 1. There's a lot of POIs in some areas. It maxes out a displaying 100,
> but we probably need to come up with a better algorithm.
> 2. The icons suck, but they're only ones I could find quickly. I'm
> thinking of extracting the icons from Osmarender.
> 3. Only a few tag types are supported, basically the ones I could find
> images for. Actually, I suppose the POI rules could be copied from
> osmarender too...
> 4. The popups suck rocks too. Anybody know a site with OL popups that
> don't suck?
> One direction is see for this is a public transport layer, displaying
> bus stops and stuff, but I couldn't find any suitable images for
> anything other than trains.
> I think this method is better than the POIs on the tiles, since here
> we can make them selectable (choose which things to see).
> Anyway, if people like it I'll move it to dev, so it'll be much
> snappier. Just after I work out how to create a postgres db there...
> Have a nice day,

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