[postgis-users] points from st_distance

Paragon Corporation lr at pcorp.us
Wed Feb 11 08:26:53 PST 2009

You are correct there is no function for doing this.  We have on occasion
needed to do this ourselves and what we usually do is 
1) first find the minimum distance 
2) figure out which point/pointset on the geometry satisfies the minimum
distance using buffer and intersection (with minimum distance being the
buffer distance).
I think I have the code lying around here somewhere.
As far as ST_Distance goes.  Haven't looked at the code that closely, but it
does some sort of recursive call and there could be more than one point that
satisfies the condition and it only cares about the first one it comes
across so such a thing may or may not be quite what you are looking for.
Hope that helps,


From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
nicklas.aven at jordogskog.no
Sent: Wednesday, February 11, 2009 4:47 AM
To: postgis-users at postgis.refractions.net
Subject: [postgis-users] points from st_distance


I have a question or suggestion.

If I have missed some functionality please tell me. 

The thing is I have often needed information about from which points the
distance in st_distance is calculated.
I mean, somewhere in the function the information have to be. Would it be
possible to build a new function which 
returned the distance, startpoint, endpoint as array or something like that.

Am I right about that this functionality is missing and
am I right about that the points have to be identified somewhere in the
function and that it ought to be possible to present them in a function.

If I'm right so far I would like to come this as a suggestion.

I also have to thank you all for postgis. 
It has been a very nice experience to start handling the gis analysing and
processing in database-environment.
My next step is to try to manage any of the procedural languages. Then I
guess I can do just anything with all the points and polygons out there :-).


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