6
votes
1answer
205 views

How can I transform polylines into points every n metres in PostGIS?

Question in pretty much the same as this, but I need to use PostGIS. I have a number of polylines, and want to trasform them into points every n metres along these lines. edit: Thanks a lot to ...
2
votes
4answers
326 views

How to turn all lines into one direction?

How can I turn all features of my polyline (postgis and/or shapefile) into one direction - it doesn't matter what direction. I know how to switch the direction of lines but I have no idea how to ...
3
votes
1answer
327 views

How to join 2D polylines and DEM into 3D polylines?

I got a simple question but could not find a satisfactory answer yet: I have a road network in 2D/PostGIS and a DEM. I want to turn the road network into 3D by retrieving the Z-value from the DEM. ...
-1
votes
1answer
27 views

The command for find the object

I got error message that shows "Object has more than 1 line in polyline". What is the command to find the object that has more than one line (such as error on number 100) Thank you
3
votes
1answer
323 views

How do I find the intersection of two polylines in PostGIS?

I have a set of road conditions reported for small segments of road, and I am hoping to determine the specific subset of each segment which intersect with a route along the road so that I can draw the ...
1
vote
1answer
127 views

postgis: problems creating flow direction polyline; not all needed connections are drawn

I am using post-gis to create a polyline that describes the flow direction of water in a landscape/catchment, to use in a hydrological model. To do that I start with a regular grid (as polygon) and ...
2
votes
1answer
284 views

Postgis 1.4 - Obtain closest point of point over polylines layer (without st_ClosestPoint)

I´ve got a polylines layer (pipes) and a points layer (valves) and In Postgis 1.4 I would like to obtain the closest points but exactly on the closest polyline. In other words, i need to locate each ...
6
votes
2answers
956 views

QGIS or Postgis - How to split polylines with a point layer?

In QGIS, I would like to split the polylines in a layer loaded in the workspace with the points in another loaded layer. If a point intersects a polyline, this polyline should be transformed into two ...
1
vote
2answers
429 views

QGIS create layer with the points of the beginnings and ends of a polylines layer (without duplicate points)

In QGIS, i would like to create a new layer containing the beginning and end points of a polylines layer, but without the duplicate points that would result of adjacent polylines.