Tagged Questions

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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5
votes
1answer
488 views

How can I add an arrow to a line?

I want to have arrow heads at the end of a number of lines. I add these through Line properties --> Line decorations. It looks nice and all when displayed in the legend: But in my map, due to ...
0
votes
0answers
42 views

grass plugin in QGIS all of sudden not working as expected

The previous week I was able to use the grass scripts in the QGIS 2.0.1 Dufour toolbox, but today they do not seem to be working. I am not sure where to place a '-c' which was a solution to the same ...
3
votes
1answer
136 views

How can I move along a line (or path)?

Given a line (street, railroad, river...) I want to simulate a moviment inside this line. Example: See this picture: Say I'm in "Nagqu" and want to move to "Kunlunqial". In a time (t=0) I'm in ...
2
votes
1answer
79 views

How to make marker line thicker in QGIS?

I'm mapping railways, find that the usual cross marker line is so thin it doesn't show up in Print Composer at web resolution, and can't find any way of making it thicker, only the main line. Is there ...
1
vote
0answers
199 views

Smoothing Lines in PostGIS

I want to smooth Lines in postgis, to be more specific, I want to smooth road data from OpenStreetMap. Basicly I thought of something like this scenario. This would be a possible road segment. I ...
2
votes
2answers
116 views

Convert point file to polyline but not joining every set of points in ArcGIS10

I have a dataset that looks like : OBJECTID Shape KP DESCRIPTION EASTING NORTHING 1 Point 0.04 Span;Start 525112.2 6728715.4 2 Point 0.0506 Span;End ...
0
votes
1answer
130 views

How to draw downhill path with TileMill and KML?

I have a kml file which contains downhill paths and other points. Here is an example. I imported the file to TileMill and I used Save & Style, but nothing appeared except a few points. I think ...
2
votes
1answer
128 views

Line calculation from KML file

I am a beginner in QGIS 2 and Mac OSx Mountain Lion I need to get line length in meters for different gps waypoints. 1 I import kml file to create a new vector shape (this works fine). The projection ...
6
votes
3answers
1k views

A tool or way to Extend line by specified distance?

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 ...
0
votes
0answers
162 views

Calculating line direction in MapInfo

I have a large file of a road network. I need to calculate the value of direction (in degrees or radians) of the line segments, and save this value to a new field. I need to use MapInfo. I have ...
2
votes
1answer
169 views

How to discretise a line into grid lines

Having a line and a grid, the aim is to discretise the line into grid lines. In the following figure, the given line is in black, its intersections with grid lines are blue, the desired is set of ...
2
votes
1answer
101 views

Draw a line and a buffer around it onto the spheroid

I need to draw a line between two points and create a buffer around this line. The only difficulty is that I need to draw not a "cartesian" line but a line that is laying on the spheroid. I tried to ...
1
vote
1answer
138 views

Split polygon into lines

I have a polygon layer which looks like this . I used the QGIS multiparts to singleparts tool and also polygon to lines. In both cases i got this type of result . I want to extract polygon into ...
1
vote
0answers
72 views

Convert polygon feature to line feature

I have a polygon shape-file i need to extract the line segments where the polygon features intersect each other and also the segment where they don't. Can we automate this process or can scripting ...
1
vote
1answer
93 views

How to get a centroid of a closed line in MYSQL

I have a table that contains only closed lines (lines where endpoint is the same as startpoint). I would need to find a centroid for those lines. How would I be able to achieve it? It does not ...
2
votes
1answer
137 views

How to convert a line to points?

I'm working with QGIS and I want to convert a line into many points, does someone know how? Thanks.
1
vote
0answers
154 views

Sources for German Standardized Symbols in QGIS

German Original: Gibt es für QGIS eine Phytonerweiterung "Planzeichenverordnung"? Zur Bearbeitung von Flächennutzungsplänen und Bebauungsplänen kommt man an den Planzeichen nicht herum. ...
3
votes
1answer
243 views

What's the unit of measurements produced by “sum line lengths”?

My goal is to find the total length of roads per county for a particular state. You would think there would be a simple government spreadsheet with this information in it.... I cannot figure out how ...
4
votes
1answer
195 views

extend line to feature. programatically

Thanks in advance for any help. I'm trying to programmatically extend hundreds of lines (blue in image) to a single polyline feature (red in image). Sometimes the lines intersect each other, but I'd ...
3
votes
1answer
99 views

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

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, ...
0
votes
1answer
383 views

Qgis - need to draw exact lines (mtrs) with fixed angle

I use GIS 1.8. I have the need to be able to draw exact lines and shapes on a bing map. (This is to project a yet to be build greenhous project on a map to show what i would look like). I have ...
0
votes
1answer
177 views

Update Point ID as Start Node and End Node to Line through FME

I need your help to perform the below process in FME. I have two layers: Pole Data (Point) and Cable (Line). Cable has no ID. I want to keep the Cable which is going through the Pole. Then make the ...
0
votes
1answer
124 views

interpolate point values to line

This might be a stupid question and I apologize if so. I have count data for different trails. They are points and I would like to make an average of those counts for each trail so that each trail has ...
1
vote
1answer
194 views

QGIS offset dash line style - dash spacing does not vary with rotation

I'd like to make a USGS-style dirt road marker but with smaller dashes and bigger spacings (i.e. less duty cycle) to indicate lower quality road. First attempt = two simple lines, custom dashes of ...
0
votes
1answer
178 views

Updating a column with line direction in MapInfo

I was wondering if there is a way to update a column in MapInfo with the digitised line direction. I have two TAB files, one is complete lines and the other is sections of the same lines (both have a ...
1
vote
1answer
119 views

Remove parts of line that fall within a polygon

I have a polygon and two lines. How can I remove the portion of each line that falls within the polygon? # polygon coords <- matrix(c(-1.798123, -1.793072, -1.805767, -1.804129, -1.798123, ...
4
votes
2answers
141 views

remove segments of lines in R

I have these 3 lines: line1 <- matrix(c(-1.81209, -1.80470, -1.80616, 55.68024, 55.67947, 55.67544), ncol=2) line2 <- matrix(c(-1.80468, -1.80330, -1.79690, 55.68322, ...
1
vote
1answer
186 views

3D and 2D lengths of lines in ArcGIS

I have a 2D road segment and convert it into 3D using a raster in ARCGIS 9.3. So, what i see is that the length of 3D road segment is still the same as the 2D road. How can this be? As due to ...
2
votes
1answer
175 views

How to split single lines to represent two-way streets?

I am working on a project using city road data. The data has every road in the city visualized as lines and with directional data stored in the attribute table (one-way to-from, one-way from-to, and ...
2
votes
3answers
801 views

Efficient algorithms to split and join lines?

Referring to the Figure below: How to efficiently join segments into lines? How to efficiently break lines into segments? The above will be applied million times.
2
votes
3answers
132 views

Breaking a continuous contour shapefile into smaller parts?

I created this contour shapefile and I need to break it into smaller parts so its better to manage. I also have a line shapefile of where I want the breaks. Is there a way to intersect and break them? ...
3
votes
0answers
97 views

drawing line from points [duplicate]

I have a series of XY coordinates. I want to use these points to draw a line in ARCMAP using arcobject10.1 using c#. I have saved this in a table inside geodatabase.Am i supposed to create a feature ...
0
votes
0answers
36 views

How to change value of an Line edit dynamically

I create a form in QT4 and compile with pyuic4. it create an form.py I want to modify the value of the line edit dynamiclly with code. I put this code in the form.py but never happen: ...
0
votes
1answer
90 views

Make many lines in one layer (Python)

I what to create many lines with this code: v_layer = QgsVectorLayer("LineString", "cable", "memory") pr = v_layer.dataProvider() seg = QgsFeature() ...
1
vote
1answer
567 views

Draw lines and Move the marker at the same time with KML format

it is possible to draw a line and put the Marker in the top of the line with KML format? or have i to make two KML files, it's that to say, One KML file for the Lines and another one for The Markers? ...
1
vote
1answer
864 views

PostGIS, create line from points

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 the ...
1
vote
1answer
126 views

Why won't lines from GPX simplify/generalize/smooth?

I am working with GPX data. I imported them to ArcGIS by 'GPX to feature' and then I created lines from these points. I am trying to smooth (or simplify) the lines now, but the tools 'smooth line' and ...
0
votes
1answer
668 views

How can I create a 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?
-1
votes
1answer
314 views

QGIS and Python - create line with multiple points in postgis [closed]

How can I create a line, with Python functions, with many points that are records in Postgis? Thank you
1
vote
2answers
565 views

Creating a 3D line feature based on 3D point features

In ArcGIS for Desktop 10.0, is it possible to create a 3D line feature by drawing a line that connects 3D point features?
0
votes
1answer
116 views

In QGIS can I show just the lines in a Postgis query? How can I do that?

I have three tables in Postgresql, each table with one layer of lines. I want to show the path of an initial line to another final. Is it possible executing a SQL query? Thanks My three tables are ...
0
votes
1answer
404 views

Problems using v.split in SEXTANTE toolbox to split lines

I got this error: Or don't click "open output file after running algorithm", but there is no new shapefile created on my desktop. How to solve this problem and split lines at a specified distance? ...
3
votes
1answer
839 views

How to split line at a specified distance and getting coordinates of start and end points of each line segment?

I tried v.split in GRASS: and my notebook ran a lot of time but showed this error:bad allocation, then I click "OK", and got nothing. Are there other ways to split lines?and I hope to get 2 new ...
2
votes
1answer
295 views

How to Blink a line on a map similarly like a point blinking on map through lat lon points

how to blink a line on a map which is formed by lat lon points through linestring from database the points(lat,lon) comes which is stored in form of MultiLineString. similarly like how a point ...
0
votes
1answer
129 views

How to set the length of a line using openlayers

I'm trying edit a polygon by changing the length of some lines by code. Found this method to calculate based on the bearing. But I didn't find anything on how to calculate the bearing, before I start ...
3
votes
1answer
1k views

How does Flow Mapper 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 ...
2
votes
1answer
192 views

Shorten polylines a given distance

I have a polyline dataset with lines of different lengths. I want to shorten all polylines the same distance on both ends (e.g. 10m each side). Is there a tool or script available that could help me ...
3
votes
1answer
2k 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 ...
5
votes
3answers
4k views

Convert multiple lines into single line

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 ...
1
vote
0answers
184 views

D3, Polymaps and Lines

I'm quite new to d3 and Polymaps and I have a question to ask.. I am trying to connect two points using a line, using Polymaps and d3, my starting point is from this code that Mike provided ...