[gdal-dev] OSM driver with z_order values

[Jeff McKenna]

On 2014-11-10 11:21 AM, Jeff McKenna wrote:
> On 2014-11-08 4:00 PM, Even Rouault wrote:
>> Le vendredi 07 novembre 2014 14:48:57, Jeff McKenna a écrit :
>>> On 2014-11-07 4:49 AM, Even Rouault wrote:
>>>> The ideal would to find some syntax to do this in osmconf.ini.
>>>> Actually,
>>>> Jukka's mention of sqlite makes me think that the syntax could be SQL
>>>> evaluated by SQLite.
>>>> Something like :
>>>>
>>>> computed_fields = z_order
>>>> z_order_type = Integer
>>>> z_order_sql = "SELECT (CASE [highway] WHEN 'minor' THEN 3 WHEN 'road'
>>>> THEN 3 WHEN 'tertiary_link' THEN 4 ... ELSE 0) + (CASE WHEN [bridge] IS
>>>> IN ('yes', 'true', '1') THEN 10 ELSE 0 END) + (CASE WHEN [layer] IS NOT
>>>> NULL THEN 10 * CAST([layer) AS INTEGER) ELSE 0 END) + ..."
>>>>
>>>> And stuff in [] would be replaced by the corresponding field value.
>>>>
>>>> That's something that could also potentially be done as the ogr2ogr
>>>> level, since there's hardly anything driver specific in that, but
>>>> finding the right U.I to specify per-layer computed fields isn't
>>>> obvious.
>>>
>>> I agree, it would be very cool to be able to configure the z_order field
>>> in osmconf.ini !!!! I'm not sure what else to add to this discussion,
>>> other than that I really want this :)
>>
>> Jeff,
>>
>> I've implemented the above idea in latest trunk. I've translated the
>> osm2pgsql
>> rules (*) for the lines layer. Let me know if that works OK. The
>> implementation of the mechanism is rather generic, so it could
>> potentially be
>> used to do many other things.
>>
>> That would be cool if folks could share a link to their "operational"
>> osmconf.ini so that we can link to it from the driver documentation
>> page. The
>> default one is probably too simple for some uses.
>>
>> Even
>>
>> (*) when you compare osm2pgsql and imposm rules, there are differences.
>> osm2pgsql uses z_order = 5 for railway, whereas it is 7 for imposm. For
>> highway = xxx_link, osm2pgsql uses the z_order of highway = xxx, whereas
>> imposm uses 3. And the values of secondary and primary are differents
>> (due to
>> the difference for railway likely)
>>
>
> Hi Even,
>
> I've updated my GDAL version and am ready to test this change.  I am
> wondering though if this "computed_attributes=z_order" can be applied to
> not only lines, but also points and multipolygons.  I will add that into
> my osmconf.ini and test to see.  I will update this thread with my
> results soon.
>
> PS. thanks for the z_order addition!!!!!!
>
> -jeff
>
>
>

Ah I think I must figure out the necessary 'z_order_sql' SELECT for 
points and multipolygons.  Ok understood.  Will get back to you soon :)

-jeff




-- 
Jeff McKenna
MapServer Consulting and Training Services
http://www.gatewaygeomatics.com/