Used for questions about making polyline features

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17
votes
3answers
3k views

How can I switch line direction in QGIS?

Something that is hopefully pretty easy. I would like to be able to swap the direction of a polyline/line in QGIS. I made a custom tool to do this in MapInfo a couple of years ago, however I can't ...
17
votes
3answers
3k views

Find tunnel 'center line'?

I have some map files consisting of 'polylines' (each line is just a list of vertices) representing tunnels, and I want to try and find the tunnel 'center line' (shown, roughly, in red below). I've ...
13
votes
7answers
3k views

Creating trade flow maps in ArcGIS for Desktop (or any free software)?

I am trying to represent trade flows on a world map where the size and direction of arrows indicate the exports/imports of a given country. This type of map is commonly found in magazines and ...
12
votes
6answers
3k views

What tools in Python are available for doing great circle distance + line creation?

I need to use Python to create a great circle distance -- both a number, and preferably some kind of 'curve' that I can use to draw in a client-side map. I don't care about the format of the curve -- ...
12
votes
4answers
3k views

How to create one-sided buffers or parallel lines in PostGIS?

I'm looking for a way to create so-called one-sided buffers or parallel lines in PostGIS. Example: 1. buffer, 2. one-side, 3. both-sides I've found some discussion on the mailing list from 2009 and ...
11
votes
5answers
7k views

Convert XY points to a line?

Someone mistakenly saved a GPS track as waypoints and then sent them along to me in a .csv file. They want a line back (shapefile). What's the simplest method to convert this to a line? Available ...
10
votes
2answers
1k views

How can I make a polyline wrap around the world?

I am using leaflet maps to create a representation of a round-the-world challenge. I would like to add a polyline which heads east from tokyo and then appears west of south america on the map - but ...
10
votes
3answers
1k views

Leaflet: how to draw curved lines?

So, I'm trying to draw curved lines in my application which is based on a Leaflet map. As far as I know Leaflet does not support drawing curved lines at the moment, so my question is really more ...
10
votes
5answers
3k views

How can I map a matrix of origins and destinations in QGIS?

I have a central point on a map, and I have other points in a separate layer (the location of a venue, and the origin cities of the venue visitors). Is there a plugin which would generate output ...
9
votes
6answers
7k views

How to join lines in QGIS?

In QGIS, I have two lines. The endpoints are near each other, but not quite aligned. I'd like to turn the two lines into one, with the two endpoints merged into midpoints. The closest I've been able ...
9
votes
4answers
2k views

Connecting line features and determining the length of the longest line

I have a line feature (see image) representing a river that I created using the Stream_to_Feature tool. The attribute table contains several records representing different lines - the problem is the ...
9
votes
2answers
5k views

Using python in ArcGIS, create a line of varying distance from an origin point

What I'm trying to do is create a line feature from a single point, using a set distance and angle. Using ArcGIS and Python (I hope). Here's the scenario: Say I have a point at these coordinates: ...
9
votes
4answers
8k views

How to make a one part polyline from a multipart polyline?

I have a polyline which is divided into multiparts and these parts are not well ordered so that the vertex's ID are not following the polyline's plotting. This polyline is a representing a bus line ...
9
votes
2answers
613 views

Scriptable alternative to ArcScan (particularly vectorising lines within tolerances)

Sadly the answer to this question suggests that it is not possible to script ArcScan from within a python script. Therefore, does anyone know of any alternatives to ArcScan (either within ArcGIS, or ...
8
votes
4answers
2k views

How to create arcs between two points in Python?

I've been working on an python script automating the visualization of live point data. I have a table with two coordinate pairs. I'd like to connect these two point with an arc of a circle or similar ...
8
votes
2answers
992 views

How can I create random points along a 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 ...
8
votes
4answers
414 views

Joining lines when direction is not known

I am struggling with this problem. I have a polyline made up of several segments. Each segment is made up of points, each point identified in 3D space by coordinates and elevation. Together, if ...
7
votes
1answer
580 views

How to determine the longest line segment within a polygon that passes through its centroid?

A PhD student approached me recently asking how one would determine the longest straight line that passes through the centroid of a polygon, the output being a polyline rather than just a table of ...
7
votes
2answers
289 views

How to derive vehicle paths from timestamped location data?

I've got a bunch of location data for snow plows. There's a unique id for every plow, a timestamp, and x & y coordinates. Instead of knowing where hundreds street plows were at one minute ...
7
votes
1answer
881 views

Making radial flow map showing curved lines over short distances (20km) using ArcGIS for Desktop?

Esri have provided instructions on how to make a radial flow map but I think the curved lines will only be produced over a long distance, like half the globe. For short distances (20km) a geodetic ...
7
votes
3answers
576 views

How to create transects from polygon centroid?

I have mapped potential study sites using polygons. What I want to do is create 9 125m transects spaced 75m apart. The center point of the middle transect needs to be the centroid of the polygon. Do ...
6
votes
4answers
985 views

How can I get my GPS track data into a graphics program?

I'm using a Garmin Edge 705 bike GPS/computer unit, which produces .gpx files. I can use the standard software it comes with to plot on Google Maps etc, but I'd like to be able to output just a vector ...
6
votes
5answers
2k views

How to create points in a specified distance along the line in 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 ...
6
votes
3answers
3k views

Convert Shape Polyline-M to Polyline

I have some pretty old software that I am forced to use (no option). It's old enough that it doesn't recognize shape files of type Polyline-M, it only recognizes shape files of Polyline. I have a ...
6
votes
4answers
888 views

Deriving separate polylines from coded points using ArcObjects (Figure inside)

I have a single point featureclass that represents the left and right sides of a landform (the points are coded as either 'right' or 'left'). Visually I can pick out and digitize two lines along these ...
6
votes
2answers
539 views

How to create line with exact same length over and over again?

I need to draw 30 meter lines in specific places. Ctrl+l is too annoying to do everytime. Is there a easy way to define specific same length for a line that I need to draw many times?
6
votes
3answers
2k views

Connecting markers by following the roads in Google Maps

I have many markers in a kml file. All the markers are on the roads. I wonder if there is a way to process the data and connect the markers by following the road? Of course, the markers should not be ...
5
votes
9answers
8k views

ArcGIS: Create a line layer from a point layer and csv data file

UPDATED DECEMBER 20 I have a Regular point layer and a csv file that has the same ids as the point layer. The csv file is organized as ID From To Weight -- ---- -- ------ 01 ...
5
votes
3answers
1k views

How to create spider diagrams (hub lines) in PostGIS?

I'm rather new to PostGIS but I have done a lot of reading. One thing that I have been searching for is a function that allows users to create a "spider diagram" (also called "desire lines" or "hub ...
5
votes
2answers
6k views

How to write a script that will automatically draw lines from one point to multiple destination points? (ArcMap 9.3)

I need to create lines from an airport to numerous destination locations. The destinations change often, so drawing them manually becomes tedious. I want to create a script that will draw them ...
5
votes
2answers
971 views

How to create a shapefile consisting of 2 lines using Python OGR?

How would you create a shapefile consisting of 2 lines using Python OGR? First line is no problem, but how do you reuse MyLine and Feature objects to create the second line? Ultimately this will ...
5
votes
2answers
123 views

Can someone clarify some details about freehand line tracing in QGIS?

I have read several tutorials and questions here on this site, but I have some lingering questions/doubts that I would like clarified. My project is tracing roadways from a 1926 map so that I can ...
5
votes
1answer
959 views

How to automatically create all possible polyline routes connecting many point locations around a polygon obstruction?

Lets say I have 30 ports on the west of an island, and 30 on the east, and need to calculate all possible shipping distances between each and every port, with the routes having to steer around the ...
5
votes
1answer
268 views

How to draw a line between two places with via-points?

I have prepared a GPS-tracking dataset, currently consisting of one table with stopping points and one table with the raw GPS-points. The first table contains a column for any stopping point showing ...
5
votes
3answers
922 views

How to find line length in QGIS while editing?

I am using QGIS (before, I used ArcView). I would like to know if there is any way during the editing phase of a vector (line or polygon) to know the length of the line (total and partial) that is ...
5
votes
1answer
252 views

Creating dynamic links between features

I currently want to create links between 2 features. Ie., I have 2 basins that flow out and I want to use a line/polyline to have a link out of them and both point to a common 3rd feature, indicating ...
4
votes
6answers
7k views

How to divide a single polyline feature into multiple features based on points located on it?

I have a shape file that contains the bus route information for a city. I want to do two things.. Merge all the existing rows so that just one feature represents all the routes... I have a Points ...
4
votes
5answers
20k views

How to connect points with a polyline in ArcMap 10?

I have a layer containing a few hundred points representing a survey track. The points are laid out in chronological order in the corresponding attribute table. How can I have ArcMap 10 automatically ...
4
votes
4answers
4k views

Merge overlapping lines in ArcGIS

I have a polyline shapefile containing a number of lines, some of which overlap. By overlap, I mean that they follow exactly the same path for some of their route, but also have bits that are not ...
4
votes
6answers
2k views

script for automated line drawing procedure for set of start and end points

A colleague conducted a field survey and recorded the start and end points of the transects with a GPS. These points have been imported to ArcMap 9.3 as 2 point layers. Both layers have a "transect ...
4
votes
4answers
1k views

How to determine a point lays within a polyline in arc engine?

I recently asked a similiar question on this, however I needed to know if there is a way to solve this if I only have a IPolyline Feature, and not the whole layer. I want to know if I can determine ...
4
votes
1answer
473 views

How to create polygon from xy data?

I have huge number of x and y data . these are left longitude,right longitude,buttom latitude and up latitude. each row is an extent of a polygon.i'd like to create a polygon using these data without ...
4
votes
3answers
906 views

Get part of polyline based on 2 points in Arc Engine

Currently I have a layer with polylines; in another layer, I allowed the user to create 2 points on the polyline. I want to know if there is a function for the polyline feature that I can use to get ...
4
votes
1answer
456 views

Why is my polyline on the wrong bearing?

I am trying to overlay duplicate segments of polylines on a map via javascript. I am using latlon.js and geo.js from here The idea is that a user can input the distance they have travelled and when ...
4
votes
1answer
411 views

Convert Landmask file into WKT Polygon

I have a land mask file in netCDF (also in ascii, if needed) which basically consists of a lat/long pair and a boolean (1 or 0) determining if that value is over land or not. The thing is, I'm not ...
4
votes
2answers
1k views

Tracklogs to single line OR several lines to one line?

Setting: I have several trucks driving out of my factory delivering goods and coming back for more deliveries. These trucks are equipped with GPS so that they may return tracklogs to me. These ...
4
votes
2answers
257 views

Draw two separate lines from A to B and B to A

I have an Origin-Destination table like this Origin Destination Value A B 10 B A 100 A C 120 ... For all the locations A, B, C... I have another table indicating their location (Lat and Lon) Is ...
3
votes
2answers
768 views

Generate non-overlapping shapes from a buffer

I have a collection of points, and I need to generate shapes around these points. Let's assume that these points are locations of offices and that the shapes are the 'area of responsibility' around ...
3
votes
1answer
197 views

How to represent Typhoon(s) wind speed using Quantum GIS / PostGIS?

I am not completly new to GIS (was taught ArcGIS at Uni) but I would still consider myself (especially compared to all these experts here) a newbie in QGIS or PostGIS. I want to display the ...
3
votes
3answers
1k 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 ...