[OSM-talk] OSM at Home (map tiles)

[Etienne]

On 10/7/06, OJW <streetmap at blibbleblobble.co.uk> wrote:
>
> On Saturday 07 October 2006 11:02, SteveC wrote:
> > Awsome
> >
> > now if only this did map tiles....
>
> Could be modified to render lat/long squares (just use a grid instead of
> the
> city database).  I'll put my PHP code onto SVN later if someone wants to
> try
> that on their own server.
>
> How accurate are the edges of osmarendered images?  If I download data
> from
> latitude 50.1 to 50.2 and render it (using inkscape with the -D option to
> do
> the entire drawing), is the bottom of the image guaranteed to represent
> 50.1N
> exactly or is there overlap?


When you grab data from the OSM server via the API it returns all segments
that cross the specified bounding box.  Osmarender, by default, calculates a
new bounding box that includes all the segments returned from the API, so
this is usually bigger than the area requested.

The latest version of Osmarender provides a way of clipping the rendered
result back to the original bounding box.  This entails adding a <bounds>
element to the .osm file.  Ideally someone could change the API to include
this element automatically.

There are one or two other edge effects that might become apparent if trying
to generate tiles using Osmarender, but I think they are relatively minor.

Etienne





Regards,
>
> OJW
>
> p.s. thanks to gagravarr, who's been testing the client and managed to
> render
> 251 maps last night:
>
> http://almien.co.uk/OSM/Places/?action=stats
>
>
>
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