[Talk-us] Tagging of county roads

[Lars Ahlzen]

On 5/28/2010 11:04 AM, Phil! Gold wrote:
> * Nathan Edgars II<neroute2 at gmail.com>  [2010-05-28 01:31 -0400]:
>> I don't know why there hasn't been any work on rendering U.S. Highway
>> and Interstate shields with a simple pattern match of "US *" and "I *";
>> it doesn't need to be perfect, just a reasonable outline.
>
> [...]
>
> I've seen that the TopOSM people are rendering US Highway and Interstate
> shields, but I haven't looked to see how they're doing it yet.

For TopOSM, there's some preprocessing when importing the planet dump to 
extract the actual digits. It might be possible to do this directly in 
the query, but there are a lot of special cases.

Otherwise, it's basically just some pattern matching in the query for 
the mapnik layer. For example:

<Layer name="interstateshields" status="on">
     ...
     <Datasource>
         ...
          <Parameter name="table">
          (select * from us_osm_line where (highway = 'motorway' or 
highway = 'trunk') and (ref like 'I %' or ref like 'I-%') order by 
z_order) as interstateshields
          </Parameter>
     </Datasource>
</Layer>

-- 
Lars Ahlzen
lars at ahlzen.com