Questions tagged [line]

A set of ordered co-ordinates that represent the shape of geographic features too narrow to be displayed as an area at the given scale (contours, street centrelines, or streams), or linear features with no area (county boundary lines)

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29
votes
2answers
54k views

Draw lines from points in QGIS

I have a point layer and need to draw a line passing through or in the vicinity of the points (up to 0.5m ditance between the point and the line). The nodes of the line will recieve the attributes of ...
22
votes
2answers
6k views

How can I merge/collapse nearby and parallel road lines (eg. a dual-carriageway) into one single line?

I have a shapefile from OSM which contains all the roads within a city. Larger roads (like dual-carriageways) seem to have 2 parallel lines. I'd like to collapse / combine those into 1 line so I can ...
21
votes
2answers
1k views

Drawing wavy, wiggly lines in QGIS?

Is there a QGIS function or plugin to draw wiggly line? I have used Spline Tool to manually draw some waves, but it is time consuming. If possible, I would like to draw something like: Inkscape ...
20
votes
6answers
33k views

Creating points in specified distance along line using QGIS?

I want to use QGIS creating points along the line, but in specified distance. I found two GRASS tools in SEXTANTE Toolbox: v.to.points v.segment I tried v.to.points, setting the maximum distance ...
19
votes
2answers
64k views

How to read a shapefile in Python?

My question is an extension of Vertical lines in a polygon shapefile. Kindly refer to that question first. What you will see is a method of generating vertical lines with respect to the bounding box,...
18
votes
4answers
13k views

Finding centrelines from polygons in QGIS?

I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file.
18
votes
3answers
2k views

Zigzag Line Symbol in QGIS

I'm looking for a zigzag line symbol in QGIS. Is there perhaps an easy way to do this that I'm missing? I have tried creating a marker line using a simple triangle marker (^) and adjusting the size of ...
15
votes
4answers
5k views

Elevation profile 10 km each side of a line

How can I get an elevation profile for a band of terrain? The highest elevation within 10 km (on each side of the defined line) should be taken into account. I hope my question is clear. Thank you ...
14
votes
6answers
5k views

Convert line shapefile to raster, value=total length of lines within cell

I have a line shapefile representing a road network. I wish to rasterize this data, with the resulting values in the raster showing the total length of the lines that fall within the raster cell. The ...
14
votes
1answer
25k views

Cut polygon shapefile by line shapefile

I have two shapefiles, a polygon shapefile (lake) and a line shapefile (boudary) I want to create a new shapefile "polygon to the north of the boundary" What tool can I use in QGIS or other free GIS ...
14
votes
2answers
5k views

Moving points onto lines (~neighborhood)

I do have two vector layer, of which one is a point layer based on "events" by remote sensing and the second one is a line layer from local research. In my case these are earthquakes and tectonic ...
13
votes
5answers
22k views

Convert a line to polygon

I have a shapefile with city areas but unfortunately the shapefile only contains single lines. The shapefile looks like this: I want to convert those lines to an area-polygon shapefile in QGIS. I ...
13
votes
1answer
3k 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 ...
12
votes
5answers
62k views

Creating polygons from lines using ArcEditor/Standard level license of ArcGIS Desktop?

I am trying to create polygons from a line layer of lots and concessions (large blocks of land in rural areas). The lines are mainly grid style as they intersect mostly at right angles. I need to ...
12
votes
3answers
26k views

Extract Raster from Raster using Polygon shapefile in R

I am new to R and using the raster package. I have a problem extracting polygons from an existing raster file. If I use extract(raster, poly_shape) function on the raster it always creates a list ...
12
votes
6answers
23k views

Partitioning Line into Segments using ArcGIS Desktop?

I have a shapefile of U.S. states. I extracted the boundary between two states, resulting in a line segment. For example, the boundary between Georgia and North Carolina. Is there a way to ...
12
votes
4answers
5k views

Create voronoi diagram from line segments

I'm looking for a way to create a voronoi diagram based on line segments instead of points. See the example below (taken from this presentation). Ideally I'd like something I can script from Python, ...
12
votes
2answers
294 views

Aggregate Lines Based on Distance between Segments

I have a VectorTile basemap that I am optimizing, (working on reducing the size of individual tiles), the major chunk of tile size is road data (geometry and attributes). I am working on simplifying ...
11
votes
2answers
2k views

Showing which way line features are oriented in QGIS?

I'm working on QGIS on a street shp file which has Left From, Left To, Right From, Right To fields fields, building a geocoder. I need to know which way these features are oriented, which I think is ...
11
votes
5answers
4k views

Measuring straightness of a curve segment (represented as a polyline)

I'm working on an automatic elevation contour labeling algorithm and one of the factors that I want to take into account when deciding the positions of labels is how "straight" a particular segment of ...
11
votes
1answer
44k views

Calculating elevation profile for a polyline in ArcGIS 10?

My elevation data is a floating point tif. I have a road for which I need to calculate the elevation profile, but I can't see the tools to do this. Can I do this with ArcGIS, with spatial analyst/3D ...
11
votes
2answers
1k views

Create “mean” line from multiple lines using QGIS

I have multiple lines features (also have them in multipoints...) representing similar path (mountain trails, in this case) with various GPS precision, resulting in many lines close to each other, but ...
11
votes
2answers
2k views

Creating line (closest vertex to line) using ArcGIS Desktop?

I'm using ArcInfo 10 SP3. I am working in reorganising our utility data. Two years ago, we have started collecting Private Service water line. We still have a lot of them to extract from old ...
11
votes
1answer
3k views

Is there a way to split polygons by several lines in QGIS?

I have a polygon (.shp) and a line (.shp) layer. I want to split the polygon in several pieces along the lines that overlap the polygon. Afterwards I want to edit each polygon separately (attribute ...
10
votes
6answers
7k views

Get a point on a polyline from end points given distance along poly line

I have start point and end point of a polyline. How can I get a point on that polyline from end points specified by the given distance. How can I get this by using arcpy provided that this script ...
10
votes
1answer
5k views

Intersecting lines to get crossings using Python with QGIS?

I have a set of lines representing bus lines. Some of the lines are overlapping and take the same roads. I am able to extract the nodes. However I am interested in extracting only crossings like ...
10
votes
2answers
2k views

Creating random points along polyline in QGIS?

I am trying to create random points along a polyline shapefile in QGIS. Basically, like the 'random points' tool in 'research tools' but for polylines instead of polygons. I have tried converting ...
10
votes
4answers
7k views

Breaking a dynamic text line in data driven pages

I am using data driven pages and some of my dynamic text attributes are too long for my layout. Is there a way to break the line into 2 or more lines with out editing the data? Example: FROM Billy ...
10
votes
1answer
5k views

How does FlowMapper Plugin work?

I downloaded the FlowMapper plugin for Qgis and I can't seem to find any information on how it is supposed to work... Also the text seems to cut-off and not fully showing for the input fields so I'm ...
10
votes
1answer
4k views

How to split a line into a specific number of parts?

I've seen a lot of questions involving splitting a line with the help of a point layer. I want to split a line in fractions of its length. For example, I have a line 400 meters long, I want to split ...
9
votes
4answers
13k views

Checking "connectedness'' of line shapefile in ArcMap?

I inherited a line shapefile in ArcMap that is used to represent a road network. The problem is that the road network is pretty large and it is impossible for me to: Tell if the end of each line (...
9
votes
2answers
968 views

Drawing line between points at specific distance in PostGIS?

I have a data of points along the streets, I would like to turn those dots into simple coloured lines. Any pointers what this problem may be called or any algorithms that can help me solve this? I ...
9
votes
3answers
7k views

Extending line by specified distance in ArcGIS for Desktop?

I have a purely aesthetic layer which has arrow symbols. Some aren't showing up right because the line is too small. I have selected maybe 50 records where I need to extend this line by a given number ...
9
votes
4answers
2k views

Creating polygon connecting endpoints of multiple lines using ArcPy?

I'm trying to figure out how to create a polygon that connects all the endpoints of a shapefile containing a set of polyilnes with pythonscript in ArcGIS, I'm having trouble doing this as the order of ...
9
votes
1answer
9k views

How do I create a SpatialLinesDataFrame from a dataframe?

I have created a data.frame in R . I want to get SpatialLinesDataFrame as a result so I understand that I have to convert the data.frame into lines, the lines into SpatialLines and the SpatialLines ...
9
votes
1answer
6k views

Creating line from points using PostGIS?

I have a PostGIS table with position data of numerous vehicles and want to create lines from these points. Data can be selected by vehicle id and ordered by timestamp but how to create lines from ...
9
votes
1answer
5k views

Interactive and dynamic map with wind data in R leaflet?

I have some data like this : longitude latitude speed direction 1 6.10722222 46.23639 4 360 2 6.95416667 43.54694 4 360 3 7....
9
votes
1answer
2k views

Is there a way to automatically snap loose points of lines to close by vertices with Quantum GIS?

I have a vector layer of lines that were drawn with the snapping option off. I need to have them snapped but, there are hundreds of lines. Is there any solution to do this automatically or semi-...
9
votes
1answer
574 views

Merge adjacent parallel lines and add count as attribute in QGIS?

I have a layer containing multiple lines representing flown tracks of airplanes. My goal is to create maps to analyse the flow of traffic in certain airspaces. I would like to merge all parallel, or ...
8
votes
1answer
8k views

Creating line with three points with Python in QGIS?

I'm new to Python and I'm having some dificulties. I want to create a simple layer with a line in the console of QGIS with Python. How can I do that?
8
votes
3answers
38k views

Converting multiple lines into single line using ArcGIS Desktop?

I've no idea if this is basic or what but I have this data that contains multiple lines (forming a polygon shape). I want to convert those lines (multiple - each with a start and end point) to a ...
8
votes
1answer
380 views

Labeling polygons along their boundaries using QGIS?

When labeling polygons (not polylines!) in QGIS, is it possible to label them along their borders rather than their area? I know I could convert polygons to polylines and then label them, but I am ...
8
votes
1answer
1k views

How do I make line symbols intersect cleanly without showing edges in QGIS? [duplicate]

I digitised a map showing electric grid lines. I merged a number of lines into a single feature. Now, I'd like these lines to be displayed so that the intersections appear continuous. At the moment, ...
8
votes
1answer
14k views

What units are shape_length in?

When generating polylines from a series of points, I used "Points to Line" tool. From this, Arc generates a polyline feature class, which includes the attribute shape_length. What units are these ...
8
votes
2answers
3k views

Automated creation of perpendicular lines between a point layer and a line layer

I am using QGIS and I am looking for a script, or a plugin, that can create a large number of perpendicular lines from a point layer to lines in a separate line layer. So far, I've tried to use the ...
8
votes
3answers
2k views

Calculating avg distance between two non-parallet lines?

I'm currently working on creating a data model that will allow the analyst to digitize two non-parallel lines of approximately the same length. Currently the methodology is to divide the lines into 11 ...
8
votes
1answer
2k views

Automated removal of dangles / loose ends in line with QGIS?

Here's what I want to do: The original line is a dissolved osm extract of ways, which I want to simplify to one continous line without dangles / loose ends (red x's in picture). I found the network ...
7
votes
2answers
3k views

Creating polygons from line segments using PostgreSQL and PostGIS

Is there a PostGIS function that creates polygons from multiple line segments? I want to convert the pictured thirteen lines to four polygons. All lines belong to the table "boundary" (gid, geom). I'...
7
votes
1answer
3k 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, ...
7
votes
2answers
8k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...