Re: [OSM-dev] shortest streets
Stephan Knauss wrote: So could you specify a better projection that would be equidistant? The data here uses 900913. Would 4326 be equidistant? FWIW, this is what I'm using on my cycle map: ST_length_spheroid(transform(way,4326),'SPHEROID[WGS 84,6378137,298.257223563,AUTHORITY[EPSG,7030]]') Note the space in WGS 84. Is there a difference between st_length() and length()? They both return the same values (at least for 900913). Same thing, but the ST_ is the newer version, thought up to distinguih spatial calls. Postgis manual has a similar query to sum up the length of ways. Why is it working there? Different projection? I guess it's just an example of the ST_length() function as is, not taking into account any projection issues. -- Lennard ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] shortest streets
Thank you for your thoughtful suggestions. I'm a n00b, so I'm not sure if I have to setup my own instance of the database to run this query or, if not, where I should go next. Any additional suggestions or direction would be appreciated. --Yumi On Thu, Sep 17, 2009 at 4:54 AM, Lennard l...@xs4all.nl wrote: Stephan Knauss wrote: So could you specify a better projection that would be equidistant? The data here uses 900913. Would 4326 be equidistant? FWIW, this is what I'm using on my cycle map: ST_length_spheroid(transform(way,4326),'SPHEROID[WGS 84,6378137,298.257223563,AUTHORITY[EPSG,7030]]') Note the space in WGS 84. Is there a difference between st_length() and length()? They both return the same values (at least for 900913). Same thing, but the ST_ is the newer version, thought up to distinguih spatial calls. Postgis manual has a similar query to sum up the length of ways. Why is it working there? Different projection? I guess it's just an example of the ST_length() function as is, not taking into account any projection issues. -- Lennard ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] shortest streets
yummy goop schrieb: Thank you for your thoughtful suggestions. I'm a n00b, so I'm not sure if I have to setup my own instance of the database to run this query or, if not, where I should go next. Any additional suggestions or direction would be appreciated. To run such queries you'll need a PostGIS database and feed a planet-dump into it. The Planet-Dump is about 6 GB compressed XML and the postgis DB will be around 65 GBs. Instructions can be found at http://wiki.openstreetmap.org/wiki/Mapnik http://wiki.openstreetmap.org/wiki/Osm2pgsql http://wiki.openstreetmap.org/wiki/DE:Mapnik (german but much more detailed, you may want to use your favorite translation tool) Peter ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
[OSM-dev] shortest streets
Hi, I've been given a project to look at dead-end streets, specifically short ones under the assumption that these may represent incomplete development. How can I search OSM for: - the shortest streets in my city/country/planet - streets which are long but have many short, discontinuous segments Secondly, what tools/environment do I need to query and parse the results? I would appreciate any help or direction here. Thanks, --Yumi ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] shortest streets
yummy goop wrote: How can I search OSM for: - the shortest streets in my city/country/planet something like this? select osm_id, st_length(way) as length from planet_osm_roads order by length asc limit 10 31970890;0.00747434498740587 32782134;0.01093132 29014067;0.019995529652 29058352;0.019997764806 28726755;0.02040745 29014076;0.02186265 6477976;0.022360680212323 29058350;0.029995529632 32969614;0.0316227758948597 27320124;0.0316227758948597 Stephan ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] shortest streets
Stephan Knauss wrote: something like this? select osm_id, st_length(way) as length from planet_osm_roads order by length asc limit 10 Something, but not exactly that. ST_Length(way) is in projected meters, which varies with latitude. -- Lennard ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] shortest streets
2009/9/17 yummy goop yummyg...@gmail.com: Hi, I've been given a project to look at dead-end streets, specifically short ones under the assumption that these may represent incomplete development. That may be too simplistic assumption, recent developments I've been mapping out basically have turning circles tacked onto the side of the bend, you might want to exclude anything with the end node having highway=turning_circle, maybe highway=noexit too ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
