[OSM-dev] Slippy Map, automatic Tile Rendering

Frederik Ramm frederik at remote.org
Fri Jan 19 10:11:04 GMT 2007


> Wouldn't it be better to actually render the high-zoom tiles properly
> instead of scaling the low-zoom ones? We don't want every side road in
> the high-level maps, only motorways and other major roads.
> As I understand it, the reasons for the scaling is that Osmarender
> doesn't work with very large datasets.

I was under the impression that - unless the area is empty - even  
*downloading* the data through the API was impossible if you request  
an area as big as a level-7 tile.

Just to clarify, here are example sizes for the low-detail tiles:

level-7: Latitude: 5.61 to 8.40 / Longitude: 47.81 to 50.62
level-8: Latitude: 7.01 to 8.40 / Longitude: 47.81 to 49.21
level-9: Latitude: 7.71 to 8.40 / Longitude: 48.51 to 49.21
level-10: Latitude: 7.88 to 8.05 / Longitude: 48.86 to 49.04

Trying to download the level 7, 8, or 9 bounding box (through josm)  
gives me an error 500 from the API. Only the level-10 download works.

> So we have to a) filter the data
> based on tags and maybe b) joins segments close to each other. Both
> don't seem too hard to do. For a) at least there is already a  
> program in
> the subversion, which I have used to generate a map of the German rail
> network only. So that can be used already.

Presumably operating on the planet file, not on live data? That would  
be possible but I don't like the approach because of the built-in  
delay. A railway line entered on Tuesday would only show up on the  
low-detail maps a week later...


Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'

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