[postgis-users] Postgis - Line to Point distance

[Pedro Doria Meunier]

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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
>
> ----------------------------------------------------------------------
>
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