A sequence of point coordinates referring to the line segments connecting them, as used to represent a one-dimensional feature or object.

learn more… | top users | synonyms

3
votes
1answer
88 views

How to find intersected line is from left or right on another line?

There is a main LineString and its direction is known. I want to find the side of intersected lines to this main line. Example image: Black line is main LineString and red one is intersected ...
3
votes
2answers
538 views

In PostGIS, how do I merge a multilinestring into a single linestring, keeping the pieces in proper order?

I have a multilinestring made up of several pieces, some of which are facing the wrong direction. (Accessible here: http://pastebin.com/89Zcixv5 ) I think what I'm looking for is some utilization of ...
6
votes
2answers
530 views

Split lines at intersection points

I've got some linestrings covering a road network, and need to split them at the crossroads. Does anybody have any idea on how to do it? I'm using QGIS 2.4, with a Postgis 2.1.3.
3
votes
1answer
94 views

Bounding box of a set of MULTILINESTRINGs PostGIS

I have a PostGIS table with a geometry column (geom) and a type column. The geom column contains only MULTILINESTRINGs and the type column contains tags that tell me what each MULTILINESTRING ...
1
vote
1answer
92 views

How to get the LineStrings from a MultiLineString

I was wondering if there is a way I can extract the LineStrings from a MultiLinestring object. What I am really trying to do is look into a MultiLineString and see if I have a certain LineString. I ...
3
votes
1answer
170 views

PostGIS: Get closest point between geometry and Multipoint

I think my question is not that difficult for GIS professionals, but i didn't found an answer to my problem (even not in other questions). Problem: I have given two tables (table1,table2) with Points ...
0
votes
2answers
108 views

Densify a JTS LINESTRING (add points)

I have a LineString I would like to "soften" in a way that if two coordinates (vertices) in the LineString are very far apart, I want to automatically add some coordinates in between. The line ...
3
votes
1answer
325 views

OpenLayers: How to get *real* centroid of a Line Geometry/Feature?

I have declared a line geometry as: var lineString = new OpenLayers.Geometry.LineString([source,target]); then I am trying to get the centroid of this lineString as lineString.getCentroid(). But ...
1
vote
0answers
185 views

OpenLayers - Add points at vertices of line while drawing line

I would like to create points while I draw a line on my map in OpenLayers. That is, at each vertices of a line and at the end points there is a shape like a square, circle, or diamond. I have this ...
3
votes
1answer
300 views

Find the closest line vertex from the linestring using PostGIS

How to find the closest line vertex from a linestring? ST_ClosestPoint will give a point which is not from the linestring.
1
vote
1answer
64 views

ValueError when instantiating LineString from a mix of tuples and Point objects

I'm new to Shapely, and tried instantiating a LineString object from a mix of tuples and Point objects like this: >>> LineString([Point(1,2),(2,3),Point(3,4),(5,5)]) I get the following ...
1
vote
1answer
236 views

Distance Between Two Points vs Length of Linestring

So I have two points that I want to calculate the distance between. If I use: SELECT ST_Distance_Spheroid(point_a, point_b, 'SPHEROID["GRS 1980",6378137,298.257222101]') / 1000 FROM ( ...
2
votes
1answer
342 views

Merge multiple linestring features into a single multilinestring

Using QGis or ogr2ogr how do I convert a vector file containing multiple linestrings features into a single multilinestring feature? At the moment I've been doing this manually by converting the data ...
3
votes
1answer
211 views

Calculate distance between point and linestring and how to represent that on QGIS?

I have loaded my data with osm2pgrouting and I have my network with ways (Linestring) and nodes (Point). The problem is : I have a database of doctors addresses (point) and I should calculate the ...
2
votes
1answer
298 views

How to extend a straight line in postgis?

I have a postgis table of simple linestrings, each one is a straight line with just two points. I want to select every linestring, but extended from both sides by 1 meter. So i have lines, that are ...
0
votes
1answer
29 views

Geometry conversion problem.Data loss

I was trying to convert a roadnetwork table.Its geometry contains both MULTILINESTRING and LINESTRING.I converted all the MULTILINE string to Linestring using the query update all_india_merge set ...
2
votes
0answers
216 views

PostGIS: How to distinguish overlapping routes (i.e., LineStrings) based on their direction?

I have a set of routes which are represented by LineStrings in my PostGIS database. These routes represent journeys that people make. I want to come up with routes that (a) overlap, and (b) have the ...
2
votes
2answers
208 views

OSM linestring shown as point

I have loaded the following file http://openstreetmapdata.com/data/coastlines to postgreSQL. In visual studio with gdal/ogr and geos enabled: SELECT geom FROM waterpoly WHERE geom IS NOT NULL LIMIT ...
4
votes
2answers
804 views

How to group connected linestrings in PostGIS?

I have a table of streets I've selected based on a set of attributes (let's say it's speed_limit < 25). There are groups of streets that are locally contiguous; I'd like to group these sets of ...
5
votes
1answer
206 views

How to transform a set of street-segments into city-blocks, with PostGIS2?

Theoretically is possible to obtain the polygons of city blocks (urban blocks) from streets, when streets are represented by street axis (LineStrings). The urban blocks are bounded by streets, so ...
1
vote
1answer
202 views

How to cluster similar lines in PostGIS?

In PostGIS I have a large database of linestrings which I have obtained using ST_makeline function. I would like to cluster similar lines based on where the lines start and end. Here is an example ...
4
votes
1answer
391 views

Calculating “travelled distance” of a GPS track without including “stops”

I have a set of GPS tracks from a cycling event and I want to correlate their distance along the route. Problem is: when a rider stops, generally by entering a covered place, GPS keeps logging (low ...
4
votes
2answers
277 views

How to speed up a query for nearest linestring to point data

I have processed a Strahler stream order layer with a lot of river linestrings (type: Multilinestring) and their corresponding strahler number (see information here). Besides I have a point layer. I ...
2
votes
2answers
275 views

Switch coordinates in linestring

I made a silly mistake: when creating linestrings in my PostGis database i inverted the lon and lat values. Which isn't a problem for postgis itself, but for my visualization and intersections. ;) Of ...
1
vote
1answer
34 views

violates check constraint

I try to add a constraint based on geometry type to a "street" table that prevents anything except Linestring geometry or Null. alter table streets add constraint streets_geom_linestring_chk ...
3
votes
0answers
138 views

How do I simplify the straight sections of (multi)Linestring in PostGres/PostGis leaving the curved sections untouched

I have (multi)linestrings containing upwards of 5000 points and I want to perform two simplifications possibly using Ramer Douglas Peucker or alternative methods in PostGis The (multi)linestrings ...
0
votes
1answer
111 views

Why are some OSM GPX line string endpoints connected?

I am working with GPX files from OpenStreetMap to render the public transportation lines of Berlin. I converted them to GeoJSON using the togeojson script. For some reason some of the lines are ...
2
votes
0answers
300 views

How to add an offset to a GeoJSON layer in Leaflet?

Using the example GeoJSON tutorial code at leafletjs.com. Change the myLines variable so that the two lines overlap, but run in opposite directions as follows: var myLines = [{ "type": ...
2
votes
1answer
386 views

How to use makeline() function for more than 2 points in spatialite?

Is it possible to use makeline() function to make linestring geometries in spatialite for connecting more than 2 sequence points? Suppose I have four sequence points P1, P2, P3, P4. Or are there any ...
0
votes
1answer
93 views

Can I use Point as the geom type in pgrouting?

in my table i have the field geom(POINT, srid) and its populated, this table also have the source an target field witch is blank(just like pgrouting guide). I tried the function pgr_createTopology() ...
3
votes
1answer
224 views

Select linestrings containing points with duplicating M coordinates in postgis

I have a table of LineStringM geometries. Some of lines have points with same measure (M coordinate). This is a bug in initial data, that I want to clean somehow. So I need to: 1. Select all records, ...
0
votes
1answer
90 views

Simplify table of linestrings

I have a PostGIS table of linestrings representing a road network. I want to simplify the geometries such that only lines that connect road junctions are stored. At the moment the table has a large ...
4
votes
2answers
985 views

How to perform SIA or Bezier line smoothing in PostGIS?

Can anyone provide an example SQL for smoothing linestrings from postgis table using Bezier curves or Iterative Averaging (SIA) algorithm?
0
votes
1answer
68 views

Line style width property not being applied in QGIS 2.0.1

I change the line width of my style and click apply, but the property does not seem to be applying to my line data.
1
vote
1answer
121 views

Separating distinct lines in PostGIS

I have a table of linestring segments in Postgis. These segments make up distinct non-intersecting lines as shown by the diagram. To add confusion the direction of the linestrings are not uniform. I ...
0
votes
1answer
290 views

Linked point geometries to linestrings in Spatialite

I have been parsing Canada's radio system frequency open data. It's a single large table per province, containing point geometries for each station callsign. Where a point-to-point link is defined, ...
2
votes
1answer
885 views

PostGIS: Calculate the length of just the portion of linestring that intersect with a polygon

I want to calculate the portion of the linestring that lies within the limits of a polygon. Better with an image What is the length of the portion of linestring within Province A? and within ...
0
votes
1answer
281 views

Defining a WHERE clause from a subquery for a query to create a handy view

It is about my implementation from an answer of this question. It is more an postgresql issue than a GIS issue, whereas it is about geometries and spatial queries. I want to create a view from the ...
1
vote
1answer
79 views

PostGIS | Get degrees clockwise from north of a linestring's beginning and end

I have a table full of linestrings in PostGIS. I would like to know the degrees clockwise from north of the starting point of the linestring and also of the end point. I was thinking that maybe ...
4
votes
2answers
477 views

How to calculate the azimuth of a line of a multilinestring in PostGIS?

I have two spatially enabled tables in PostgreSQL with a geometry in each: First table is with POINT type, second is with MULTILINESTRING. I need to calculate the azimuth of the LINESTRING part of a ...
7
votes
4answers
612 views

How to calculate the “depth” of a linestring using postgis

I have linestring features, which look like bent linestrings, hemicycles or convex or concave linestrings. In the moment I can select the distance between the startpoint and endpoint of each feature. ...
3
votes
1answer
352 views

PostGIS: Using a polygon to 'mask' linestrings returns both multi and linestrings

I have a table of linestrings (OSM roads, in fact) that I'm displaying on a map. I want to filter them so that only those within a certain area are displayed- I've already done this with the coastline ...
4
votes
1answer
754 views

How to create linestrings with a definite angle and length, that are fixed to a point

I want to create linestrings with a definite angle (e.g. 160°) and length (e.g. 2m) that are fixed to a number of points of another linestring. So, I want to use the ST_DumpPoints function to find the ...
1
vote
2answers
561 views

Extract a LineString from LineString by two Points

I am using PostGIS2.0 and PostgreSQL9.3. I have LineString in Spatial-Ref 4326 like geom:= ST_GEOMETRYFROMTEXT('LINESTRING(60.7014631515719 56.8441322356241,60.7023117507097 ...
1
vote
2answers
241 views

Mapserver - label at beginning of line string (WMS)

I am creating a WMS service made up of linestrings pulled from a POSTGIS database I want to label the start of each line with a sequence number. At present I can label the centre of each with:- ...
2
votes
3answers
670 views

How to create a efficent linestring out of geography points using postgis

I'm trying to create a linestring out of geography points. At the moment I'm doing it like this: select ST_GeographyFromText(ST_Makeline(a.record_point)) from ( select (record_point::geometry) from ...
0
votes
2answers
525 views

How to create a MultiLineString feature with a postgis layer in QGIS

I have troubles handling with MultiLineStrings in QGIS. I added the table where I defined a column as geometry(MultiLineString, 31468) as a postgis layer in QGIS. Now I want to create features with ...
1
vote
2answers
188 views

Frequency of partially or fully overlapping lines

Let L be a set of line-segments (lines) in a two-dimensional (2D) Euclidean space that are randomly (say, using uniform random function) distributed, that is, some may overlap other(s). Overlapping ...
1
vote
1answer
1k views

How to find the intersection point of polygon geometry and multilinestring geometry in postgis

I have a polygon geometry and multilinestring geometry. How do i find the intersection of both these geometries. Both the geometries are in same reference system. Does st_intersection gives me the ...
1
vote
1answer
724 views

From a trajectory of GPS points to a multiline segment

Given a trajectory as a sequence of GPS points I would like to create a smooth linestring representing a path where a car drove. The data is stored in postgresql: the input trajectory in a table, ...