Re: [postgis-users] How to get the nearest point for a given point from a geometry of multilinestring

Thanks a lot.I will try with this and let you know the result. Thilani On Tue, Jul 21, 2009 at 10:43 AM, Kevin Neufeld wrote: > If I understand you correctly, you could first find the 2-point line segment > within your multilinestring that is within some tolerable distance to your > intersection p

Re: [postgis-users] How to get the nearest point for a given point from a geometry of multilinestring

If I understand you correctly, you could first find the 2-point line segment within your multilinestring that is within some tolerable distance to your intersection point. The endpoints of the linesegment would be vertices closest to your intersection point. Here's an old way of extracting th

Re: [postgis-users] Loop or Cursor

What kind of operation? Even an update statement might suffice. There are many ways to cleverly control the flow of an update that do not necessitate doing a loop or cursor. Also keep in mind even within a function used in a SELECT statement of a query, PostgreSQL allows you to run updates and

Re: [postgis-users] Considerations on performance: union on 59000geometries

Which version of PostGIS are you using. The upcoming 1.4 is much much faster and may do the trick for you. Its in rc2 now. Ready to release any day. There is no way the 1.3 will complete with 59,000 in one go. Leo -Original Message- From: postgis-users-boun...@postgis.refractions.net

[postgis-users] Considerations on performance: union on 59000 geometries

Hello everybody, today I tried to perform a union on 59000 geometries, but the operation seems not to complete. In no way I'm an expert in PostgreSQL/PostGIS optimization, and for sure my system is not in the perfect shape to address such operations with elegance. My questions are: * should Post

[postgis-users] Loop or Cursor

Hi I need to access a number of rows, one at a time to perform an operation on each. Under what conditions would I consider using a loop command, rather than (or with) a cursor? Bob___ postgis-users mailing list postgis-users@postgis.refractions.net

Re: [postgis-users] points to lines

ah...@elegantdesigns.ca wrote: Hello list, I have a point table with the following format: idnode_1node_2weight 1 1 2 5.4 2 1 3 2 3 2 4 6 4 4 4 1 the table is about 2,000 rows long. i was wondering ho

[postgis-users] points to lines

Hello list, I have a point table with the following format: idnode_1node_2weight 1 1 2 5.4 2 1 3 2 3 2 4 6 4 4 4 1 the table is about 2,000 rows long. i was wondering how can i convert this table into a

Re: [postgis-users] Finding the center of a street

I had the same problem, and I finally solved it outside of Postgis, with own algorithm. The algorithm was that 1. I took all segments. With segment mean here simple, "straight" line. 2. Found half or the total length of the street segments 3. Found center segment: stepped by segments until walk

[postgis-users] How to get the nearest point for a given point from a geometry of multilinestring

We used ST_Intersection function to get the cross point when roads are crossing each other. So with the output of this function we have the crossing point and now we need to get adjacent points to that crossing point from the road (where the road is a geometry of multilinestring).Is there any post

Re: [postgis-users] Precision problem

On 07/18/09 21:17, Paragon Corporation wrote: > For a geometry to be considered ST_Within, the geometry can not sit wholly > on the boundary of the other. Its an often misunderstood thing. You really > want to use ST_Covers or ST_CoveredBy. Thank you for the explanation. ST_Covers is indeed what