Used for questions about making polyline features

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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 ...
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 ...
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 ...
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 ...
12
votes
6answers
4k 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 -- ...
11
votes
5answers
8k 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 ...
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 ...
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 ...
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 ...
9
votes
2answers
621 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 ...
7
votes
1answer
898 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 ...
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 ...
11
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 ...
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 ...
7
votes
2answers
290 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 ...
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 ...
5
votes
9answers
9k 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 ...
3
votes
1answer
222 views

How can a single line be computed from multiple possibilities

I have datasets containing continuous GPS streams of data that represent routes or trails. For any given route, I probably have at least 5 (in some cases many more) different sets of data. Given that ...
7
votes
3answers
593 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
890 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 ...
4
votes
3answers
913 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
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
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
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 ...
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 ...
3
votes
1answer
769 views

How to create an offset polyline in arcpy?

I am trying to create an offset polyline using arcpy, identical to the function in ArcObjects (constructoffset). After trying to access ArcObjects in arcpy, which I found difficult for those not ...
1
vote
1answer
428 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, ...
3
votes
2answers
518 views

How to densify a polyline according to a specific length? [duplicate]

Possible Duplicate: Add vertices to lines I am using QGis 1.8.0 I would like to densify a polilyne according to a particular length of segment (ex. 200 m). I know it is possible with other ...
1
vote
1answer
661 views

Polymaps + D3+ Polyline with different width and color

I am actually working on a project which involves polymaps and D3. I was wondering if you could help me on this. I have 4 locations and I would like to draw a polyline from one location to other 3 ...
1
vote
1answer
998 views

How to create multipart line and polygon with interior ring in ArcGIS Python?

My objective is to swap X,Y coordinates of feature classes using Python and arcgisscripting. Based on help examples, I managed to write script which reads and writes all geometry types. The problem ...
0
votes
0answers
78 views

Help with building a batch model to extend radiating lines to nearest feature for multiple points

I'm new to using modelbuilder in ArcGIS 10 and was hoping I could get some help for creating a batch model to extend lines from points to the nearest feature. Here's what I need it to do: 1) ...