[OSM-dev] osm2pgsql - strange behaviour

Nick Black nickblack1 at gmail.com
Fri Jun 22 16:29:11 BST 2007


So I should be able to change the SRID to 41001 and then reproject
back to 4326 within pgsql i guess?

On 6/22/07, Artem Pavlenko <artem at mapnik.org> wrote:
>
>
> 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
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>
> Artem Pavlenko
> http://mapnik.org
>
>
>
>
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>
>
>
>
>
> --
>    Jon
>
>
>
>
> Artem Pavlenko
> http://mapnik.org
>
>
>
>


-- 
Nick Black
--------------------------------
http://www.blacksworld.net




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