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

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0
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1answer
361 views

Check if a point coordinate is between linestring coordinates

I know that, linestring is a vector and if i want to check that, if point coordinates are between linestring beginning and ending coordinates then i need to use vector comparison (x2 > x && ...
4
votes
1answer
202 views

How to transform isolines to isopolygons with postgis?

I have a table a postgis table of isolines that's defined like this: CREATE TABLE myisolines ( gid serial NOT NULL, isotime timestamp without timezone, val numeric(10,4), geom geometry(...
3
votes
2answers
64 views

PostGIS - Get a point inside a line or polygon

I need to get the center point of a line or polygon to make marker for my app. So that when you click a marker the geometry appears (line or polygon). I used ST_Centroid to make it work. The result ...
3
votes
1answer
293 views

MySQL select linestrings into a multilinestring

I have a mysql column of linestring type with 2000 linestrings (high water mark values to be more specific). I want to merge them into one multilinestring so i can see what the shape of these values ...
2
votes
2answers
184 views

How to extract a new linestring vector from a existing multipolygon in QGIS?

What I want to do: create a new line (named linestring in Postgis?) from existing multipolygon layer in Postgis. Purpose: once these lines are created, I'll run some distance calcs from specific ...
0
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2answers
201 views

Create point on a line with given distance from end in PostGIS

Does anyone know how to create points along a line (MultiLineString geometry) with a given distance in PostGIS? I'd like to create points at a regular distance over a line, which represents a ...
2
votes
1answer
55 views

How to split overlapping linestrings?

I'm new to PostGIS and a bit lost... I work with linestrings that sometimes overlap, for example: I'd like to distinguish these linestrings by splitting them like Google Maps do: I was thinking ...
1
vote
1answer
147 views

Using Geotools union() method (to combine LineStrings)

I want to combine LineStrings with common points. The scenario looks like this: I tried it using the GeometryCollection.union() method like suggested here: http://docs.geotools.org/latest/userguide/...
1
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1answer
68 views

QGIS show labels in beggining or ending points of Linestrings

I've got a Linestrings layer. Each Linestring has among other fields, these ones: id ENTRY EXIT 1 S1 E2 2 S1 E3 3 S1 E3 4 S1 E3 5 S1 E3 6 S1 E1 7 ...
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0answers
19 views

Move Dragged marker along a line String in Openlayers 3

I have a linestring and a marker on top of it. I want to drag the marker alonng the Linestring and restrict the movement only along the line. (cant drag to any other place on map). it should be ...
3
votes
2answers
267 views

PostGIS get the distance between two points over a linestring

I have a linestring: LINESTRING(-1.3326397 50.9174932,-1.3319842 50.9166939) and I select two points that lay on that linestring. I would like to get the distance between these two points (in ...
0
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0answers
19 views

Maximum likelihood Between 2 linestrings in Postgre?

I created a lot of linestring datasets and loaded them all in PostgreSQL, I want to compare said linestrings 2 by 2 using a maximum likelihood Query which would give me a coefficient proportional to ...
0
votes
1answer
40 views

Linestrings into one multilinestring

I have 2 tables "dijkstra_results_geo" and "dijkstra_results_geo_aggregate". I have a set of Linestrings in the column dijkstra_results_geo.geom_path_intermediaire (defined as geometry(Linestring, ...
0
votes
0answers
10 views

MSL/AGL bounds checking in PostGIS for Line/Polygon Intersection

I have a table with Polygons and columns defining an optional upper and lower altitudes bounds and altitude type. The Type can be MSL, AGL, or NULL, if unbounded, and can be set separately for upper ...
1
vote
0answers
27 views

Swapping start and end points of line (i.e. direction) of LineString in PostGIS?

I know that postgis has the function to find the start and end point of a line. Is there a function that can swap the start point and end point? (Note: I do not mean literally changing the co-...
2
votes
1answer
26 views

What does the GEOS LineString “normalize()” routine really do?

What does the GEOS LineString "normalize()" routine really do? GEOS has virtual void geos::geom::LineString::normalize() with the documentation: A normalized linestring has the first point which ...
1
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0answers
20 views

Linestring segment completition?

I just extracted some river paths from some old maps I acquired a few weeks ago, they seem accurate enough and will be very interesting to put against my theoretical mapping calculated by using the ...
3
votes
0answers
43 views

Can I reorder the points in a GEOS LineString?

Using libgeos, when I buffer() a polygon and then getExteriorRing() [to make a slightly smaller outline copy of the polygon just inside the original], it seems that which point on the new geometry is ...
1
vote
1answer
32 views

Convert KML polygons to lines

I've been given a KML file which should consist of linear features (train lines), but for some reason they're all represented as <Polygon> types. Each appears to have the right data, from end of ...
1
vote
0answers
74 views

Using TIGER/Line shape files, how do I get address coordinates?

I've downloaded addressfeature shapefiles from TIGER/Line on the Census Bureau website. I converted one file to CSV using ogr2ogr. I get the following sample output: WKT,TLID,TFIDL,TFIDR,ARIDL,ARIDR,...
4
votes
0answers
275 views

PostGIS 2.0 st_geomfromgml using LineString fails with invalid GML representation

I am attempting to insert a geometry into a table using the st_geomfromgml function. The GML is being sourced from a Geoserver WFS request. The function call looks like this st_geomfromgml('<?...
1
vote
1answer
301 views

Using Python in Arcmap to partition strings [closed]

I have a title "Text that remains Proposed Thing to replace" var_a = New Text I want the output to be "Text that remains Proposed New text" Currently outputs this "(u'Text that ...
3
votes
3answers
3k views

Creating point to center of polyline?

I'm trying to create a points in the middle of polylines. The data is now in the form of shapefile. Is there an easy way to do this?
13
votes
4answers
287 views

How to create lines to visualize differences between polygon features in PostGIS?

I've a PostGIS table polygon_b with some polygon features. There is also a table polygon_a which contains the same polygons as polygon_b but with minor changes. Now I want to create lines to visualize ...
2
votes
1answer
58 views

Bring a list of unsorted linestrings in order so that they form a path from origin to destination

I have a table of linestrings together with some attributes that, when displayed all at the same time, represent a connected path from an origin to a destination (each linestring has one predecessor, ...
2
votes
0answers
498 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
110 views

Get LineString length in meters (Python, GEODjango)

In a Django model, I have a LineString field which holds GPS coordinates of a street route. I know that I the .length holds the length of the LineString, but I don't know what unit the returned value ...
6
votes
1answer
5k views

How can I transform a polygon to a linestring in QGIS?

I have a polygon, imported from a shapefile in QGIS. I would like transform it to a linestring instead so I can save it as a GPX file later. How can I transform a polygon to a linestring in QGIS?
5
votes
2answers
146 views

How to use ST_Difference to create linestrings from non-intersecting polygon boundaries?

There are two tables with polygon features in my PostgreSQL database. I want to create linestring features where the boundries of the polygons are not intersecting. CREATE TABLE schema.poly_a ( gid ...
2
votes
1answer
81 views

Creating line-strings from points in MySQL

I am extracting the lat/long information from Geo-tagged images and storing them in MySQL. I want to get a line-string from the points, I looked into the GROUP_CONCAT() function but I am not able to ...
5
votes
1answer
127 views

Find all intersections of a LineString and a Polygon and the order in which it intersects it

I would like to find out all intersections of a LineString (River) through Polygons (Municipalities). I would like to list the order of municipalities which the river crosses, using linear referencing....
7
votes
4answers
5k views

How to extract POINT from a [LINE|MULTILINE]STRING

I'd like to create a vectorLayer in QGIS to display all the points that form a LINESTRING or a MULTILINESTRING stored in a PostGIS DB. I think that I need to transform all points of LINESTRING (or ...
1
vote
2answers
245 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
0answers
32 views

Postgis - Construct linestring of length N

Give a table of linestrings (roads) ogc_fid, wkb_geometry And a road with ogc_fid = X In postgis how could I construct a linestring that is of length Y metres made up of roads starting from road X?...
0
votes
1answer
37 views

Linestring in OpenLayers doesn't draw

I don't understand why my code doesn't work. If the map is displayed, the line is never drawn: <script> var long_deb = -1.28627; var lat_deb = 43.49829; var long_fin = -1.29394; var lat_fin = ...
1
vote
1answer
100 views

Finding and merging lines that touch in PostGIS?

I would like to select and merge segments that touch like in the image below. My table contains single segments with their own id (shown in the figure), I just want to isolate single "group" of ...
4
votes
2answers
74 views

Get the 2 points immediately before and after a given point in PostGIS

In the picture below: The given point is C, I would like to select A and B, but not Z (which is closer to C than B but it's not immediately after in the LineString). Note that C is always ON the line ...
4
votes
1answer
1k views

leaflet - Drawing line following the road

Short version: What I wish to be able to do is drawing a polyline along part of a road. In that way marking certain houses, along this road. Long Version: I have several houses that I wish to mark ...
1
vote
1answer
185 views

In PostGIS: how to split linestrings into their individual segments?

I have one table with many linestrings and I want to make a new table containing the individual segments of all the linestrings, no matter if they are grouped line per line or not. This is my table,...
1
vote
2answers
210 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 ...
6
votes
2answers
214 views

What controls the direction of TopoGeometry Linestrings?

In PostGIS, what if anything controls the direction that topogeometry LINESTRINGs will have when converted to geometry? It doesn't appear to be the order in which the edges are listed in the call to ...
1
vote
1answer
28 views

Finding zero-length LINESTRINGs the wrong way gives funny answer

I tried select st_astext(geom) from table where st_pointn(geom, 1) = st_pointn(geom, 2) But I get some results which don't match the criteria. For example: LINESTRING(-117.1642086 34.2779308,-117....
1
vote
1answer
107 views

Determine points where a LineString meets the boundaries of a Polygon using Turf.js

Using Turf, I'm trying to determine the points at which a line (LineString) meets the boundaries of a polygon. Turf has the ability to do point-in-polygon/point-on-line and polygon intersections etc, ...
-1
votes
1answer
48 views

JSON to line string

I'm getting a JSON return like so: [{"lat":38.660274,"lng":-90.136198},{"lat":38.6613,"lng":-90.13860199999999},{"lat":38.664634,"lng":-90.141853},{"lat":38.664634,"lng":-90.141853},{"lat":38....
0
votes
1answer
222 views

MapServer: Symbol (v-line) style that automatically follows line direction

I created this image: with: MAP SIZE 1000 1000 IMAGETYPE png24 EXTENT -30 -10 60 30 UNITS DD SYMBOL NAME "v-line-shift" TYPE vector POINTS 0 0 5 10 10 0 END # ...
5
votes
2answers
411 views

Counting self intersections of linestring using PostGIS?

Is there a way of using PostgreSQL + PostGIS for finding the number of self intersections in a linestring? I have a linestring that goes forward but in circles, and I need to find the number of times ...
2
votes
2answers
97 views

PostGIS - Merging linestrings into multilinestrings in a particular order

I have a set of linestrings, which I want to group into a single multilinestring, and in a specific order. However, when I use ST_Collect, it merges them out of order, like this: Geometries as ...
2
votes
3answers
95 views

How to remove identical lines from layer in QGIS?

I converted polygon layer to line layer using "Polygons to Lines" tool. Then I used "Split" function of the Networks plugin. What I need to do next is to remove identical lines that were shared ...
5
votes
0answers
238 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 ...
3
votes
2answers
367 views

How to recalculate the the length of a geography linestring from nearby geography point in POSTGIS?

I have a geography type linestring *route_geography geography(LineString,4326)*, its a route from point A to point B. Now I have a point C near that line. I want to find the nearest point on that line,...