Slippery Map, Zoom Levels and POIs

Is there any way to change the zoom level at which POI icons are displayed on the slippery map?

The defaults seem OK for urban areas where displaying the icons at a lower zoom level would result in too much map clutter. But, for rural and wilderness areas where POIs are few and far between it would be nice if they could be displayed at a lower zoom level. By the time you zoom in far enough to display the icons you’ve lost any sense of where you are in relation to major roads and other POIs.

Did you find anything to change the detail level in rural areas? I would also like to know if this is possible. Thanks.

I spent quite a lot of time on this and finally decided that there’s no easy way. I got mapnik (a map rendering program) running on my Mac and managed to get POI’s to display at any zoom level. But that’s really a geeky solution and not much use to the public at large. (I don’t have the resources to serve up map tiles for all comers.) I did get a message from one guy who said that a group in Sweeden is going to work on setting up a server that allows users to set the zoom level at which POI’s appear, but that was that.

One thing I did learn was that you have to be careful what you suggest. Sadly, there are some people who think that suggestion equals criticism.


Using prerendered tiles is an excellent system for delivering bulk maps to thousands of users. Negative side is that using only tiles is not a way to deliver interactive maps with user selectable contents and styles. It is unreasonable to cache tiles for all the possible alternatives There are alternative ways to give users more power to deside what will be included on the map or how it would look like. One is to use WMS service and let users select the WMS layers they want to see on the map or even point to a desired SLD style document to be used for rendering. Another way is to make a hybrid: use bulk map as a background and let users to select some additional features on top of that. An example of the latter is at
Unfortunately that example does not seem to work. It might be close to the system you are looking for. Keepright is doing the same thing but with map error data instead of POIs.

Thanks for posting JRA. I think what you said points out the great divide between those of us who just want ways to use the data and those of you who actually familiar with the inner workings. I figure I understood about 1/3 of your post. For example, I had to look up both WMS and SLD.

I can see wonderful uses for the OSM data, but there’s no easy way for me to get at it in a way that is actually useful to me.


I am mostly utilising OSM data with standard GIS software, therefore I speak about Web Map Servise (WMS) and Styled Layer Descriptor (SLD). They are not so popular among OSM folks but do have some fine features. Lets say you would only be interested to render some building outlines:,60.151649,24.955234,60.170196&SRS=EPSG:4326&WIDTH=730&HEIGHT=575&LAYERS=osm_auto%3Abuildings&STYLES=&FORMAT=image/jpeg&DPI=96&TRANSPARENT=TRUE

Or you are not interested in buildings but POIs could be nice to have on a map,60.151649,24.955234,60.170196&SRS=EPSG:4326&WIDTH=730&HEIGHT=575&LAYERS=osm_auto%3Apoints&STYLES=&FORMAT=image/jpeg&DPI=96&TRANSPARENT=TRUE

Or perhaps you want to get those both:,60.151649,24.955234,60.170196&SRS=EPSG:4326&WIDTH=730&HEIGHT=575&LAYERS=osm_auto%3Apoints,osm_auto%3Abuildings&STYLES=&FORMAT=image/jpeg&DPI=96&TRANSPARENT=TRUE

What tiles can offer is something ready made that somebody gives for you. It may look good but it is always the same. Of course that can also be achieved (in much less efficient way) with WMS:,60.151649,24.955234,60.170196&SRS=EPSG:4326&WIDTH=730&HEIGHT=575&LAYERS=osm_auto%3Aall_Europe_GK3&STYLES=&FORMAT=image/jpeg&DPI=96&TRANSPARENT=TRUE

You should see that WMS in not necessarily slow for users if the server does not have much load. Previous requests are rendered on-demand, and you can play with WMS server by changing the BBOX parameters and get maps from different places.

This was about selecting certain layers through WMS. Another fine feature (but which I have never tried myself) in WMS is the possibility to give pointer to layer rendering rules with the request. So instead of always getting the, let’s say, “Mapnik” styles from OSM the user could point another styling rules with the STYLES= parameter. There could be a library of OpenStreetMap styling documents (SLD files) to select from. No need to set up a separate services and tilecaches for every map that just has a little bit different styling. Unfortunately I cannot give any links because I couln not find any.

Something to read through is at