[OSM-dev] osm2pgsql - strange behaviour

Artem Pavlenko artem at mapnik.org
Fri Jun 22 15:47:17 BST 2007


On 22 Jun 2007, at 14:39, Jon Burgess wrote:

> Yes the code reprojects to mercator as part of the import (search for
> references to 'project'). You can switch to latlong by commenting out
> the reprojection (you'll probably also want to change the SCALE used
> for the fixed point in middle-ram.c too if you change this otherwise
> you'll lose some precision).
>
> I suppose that this SRID is wrong and should of been changed when the
> reprojection got added. Anyone know what SRID would be appropriate?
>
>

I think we can change it to 41001. Apparently there's no 'official'  
code for Mercator but google return 41001.
Artem
> On 22/06/07, Artem Pavlenko <artem at mapnik.org> wrote:
>> Nick,
>>
>> osm2pgsql projects coordinates to Mercator.
>>
>> Artem
>>
>> On 22 Jun 2007, at 13:24, Nick Black wrote:
>>
>> Hello,
>>
>> Trying to run osm2pgsql I get some strange values in the geometry  
>> columns of
>> postgis.  For example, if I import the following made up osm file:
>>
>>
>> <?xml version="1.0" encoding="UTF-8"?>
>> <osm version="0.4" generator="OpenStreetMap server">
>>   <way id="1" visible="true"
>> timestamp="2006-08-18T22:51:40+01:00" user="dankarran">
>>     <seg id="1"/>
>>     <tag k="created_by" v="JOSM"/>
>>     <tag k="name" v="Marine Drive"/>
>>     <tag k="highway" v="secondary"/>
>>   </way>
>>   <segment id="1"  visible="true"
>> timestamp="2006-08-18T22:51:40+01:00" from='1' to='2'>
>>    </segment>
>>   <node id='1'  timestamp='2006-08-15 02:08:50' visible='true'  
>> lat='1.2345'
>> lon='-6.789'>
>>     <tag k='source' v='PGS' />
>>      <tag k='created_by' v='almien_coastlines' />
>>   </node>
>>   <node id='2'  timestamp='2006-08-15 02:08:50' visible='true'  
>> lat='2.2345'
>> lon='-7.789'>
>>     <tag k='source' v='PGS' />
>>     <tag k='created_by' v='almien_coastlines' />
>>   </node>
>>
>> </osm>
>>
>> and then do :
>>
>> # select astext(way) from planet_osm_roads ;
>>
>> I get:
>>
>>  LINESTRING(-755748.02 136514.64,-867067.51 247141.71)
>>
>> Which isnt what the values should be. Is there some kind of  
>> reprojection
>> going on somewhere?  I have geometry columns and spatial ref sys  
>> set up
>> seemingly correctly, with planet_osm_roads referencing srid 4326,  
>> which has
>> the following entry ins spatial_ref_sys:
>>
>> GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS
>> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84 
>> [0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich", 
>> 0,AUTHORITY["EPSG","8901"]],UNIT["degree",
>> 0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY 
>> ["EPSG","4326"]]
>> | +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs
>>
>> I'm taking a look through the osm2pgsql src to see how the database
>> connections work, but the c++ will take me a while to figure out...
>>
>> cheers,
>>
>> --
>> Nick Black
>> --------------------------------
>> http://www.blacksworld.net
>> _______________________________________________
>> dev mailing list
>> dev at openstreetmap.org
>> http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
>>
>> Artem Pavlenko
>> http://mapnik.org
>>
>>
>>
>>
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>> dev at openstreetmap.org
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>>
>>
>
>
> -- 
>    Jon
>

Artem Pavlenko
http://mapnik.org



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