ST_Length_spheroid is perfectly great, but it does not take a line as an input :-(
2009/7/10 Pavel Iacovlev <[email protected]> > And for geometry length use ST_length_spheroid(geometry,spheroid) > > On Fri, Jul 10, 2009 at 11:48 AM, Pavel > Iacovlev<[email protected]> wrote: > > you can take the middle of the line, st_line_interpolate_point(the_geom, > 0.5) > > > > 2009/7/10 Peter Kukuča <[email protected]>: > >> Hi Pedro, > >> > >> thank you for your reply. > >> > >> I cannot use pointn, the line can be up to several hundred kilometers > long > >> and consits of up to 800 points, so this would be too rough. > >> > >> Regardinf the decond suggestion, that is exactly what I am doing now, > but I > >> don't know, which projection (srid) to transform the wgs84 data into. It > >> should work on all of the earth's surface, at least in all of europe for > a > >> start. And from what I found, the projections are usually tied to a > small > >> territory. I was thinking about mercator projection, but there is a > zillion > >> of them in postgis. And I found a post, that the one with srid 900913 is > >> working great, but I don't have that one in my postgis. > >> > >> 2009/7/10 Pedro Doria Meunier <[email protected]> > >>> > >>> -----BEGIN PGP SIGNED MESSAGE----- > >>> Hash: SHA1 > >>> > >>> Hi Peter > >>> > >>> You could use the pointn(geometry, n) for the first point of the > >>> linestring as a first approach. > >>> As far as meters are concerned here's a little example of transforming > >>> the geometry to the desired projected system: > >>> > >>> select distance(transform(u.coordinates,srid), > >>> transform(p.geometry,srid)) AS thedistance > >>> > >>> HTH, > >>> > >>> Pedro Doria Meunier > >>> GSM: +351 96 17 20 188 > >>> Skype: pdoriam > >>> > >>> > >>> > >>> > >>> Peter Kukuča wrote: > >>> > Dear sir, > >>> > > >>> > I am not sure if I am writing to the correct email address. I have > >>> > found a post on the postgis-users formu from *Rich Gibson *and this > >>> > address was next to it. > >>> > > >>> > I am using postgis for a while now and it is great. It solved a lot > >>> > of problems for me. > >>> > > >>> > However, I am now facing a problem I cannot solve. I searched for > >>> > almost two days now, but I still cannot find an answer. Here is my > >>> > problem: > >>> > > >>> > I have a database of linestrings in wgs84 projection and points in > >>> > wgs84 projection. I would like to determine the distance between a > >>> > line and a point. The ST_distance function does this very well, but > >>> > it does not take the wgs84 projection into account and also, the > >>> > result is in degrees. On the other hand, the ST_Distance_Spheroid > >>> > does take the wgs84 into accound and does give the result in meters, > >>> > but it does not accept a linestring as an input parameter. > >>> > > >>> > Is there any way i can the distance between a line and a point in > >>> > meters from the wgs84 projected input? I do not need grat accuracy. > >>> > +-5 meters is still good enough. Thank you for your tips. > >>> > > >>> > -- > >>> > S pozdravom (regards) > >>> > Ing. Peter Kukuča > >>> > > >>> > > ---------------------------------------------------------------------- > >>> > > >>> > _______________________________________________ > >>> > postgis-users mailing list > >>> > [email protected] > >>> > http://postgis.refractions.net/mailman/listinfo/postgis-users > >>> -----BEGIN PGP SIGNATURE----- > >>> Version: GnuPG v1.4.7 (GNU/Linux) > >>> Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org > >>> > >>> iD8DBQFKVv052FH5GXCfxAsRAqS1AJ0dfphFX3wrMuo+FdXVRTgmUzHRUACfUmvH > >>> 146yGHfxoVmlnt9a91rpWmE= > >>> =G70f > >>> -----END PGP SIGNATURE----- > >>> > >>> _______________________________________________ > >>> postgis-users mailing list > >>> [email protected] > >>> http://postgis.refractions.net/mailman/listinfo/postgis-users > >> > >> > >> > >> -- > >> S pozdravom (regards) > >> Ing. Peter Kukuča > >> > >> _______________________________________________ > >> postgis-users mailing list > >> [email protected] > >> http://postgis.refractions.net/mailman/listinfo/postgis-users > >> > >> > > > > > > > > -- > > http://iap.md, The future is open > > > > > > -- > http://iap.md, The future is open > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > -- S pozdravom (regards) Ing. Peter Kukuča
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