2
votes
2answers
66 views

Suggest an algorithm to measure how a node is connected to road network

I try to measure how well a node is connected to the rest of the network. If a city has a distant suburb connected with one sole road, it's connectedness is, say 1. If it's connected by 2 roads, it's ...
0
votes
0answers
134 views

QGIS 2.2 problem, loading layer into road graph

I have the road graph plugin installed, but when I try to configure it with the Settings dialogue, no layer names appear in the Layers field. I have tried various shapefiles, but the Settings dialogue ...
1
vote
0answers
24 views

What can I do in qgis to manage a WMS frequently unreachable?

In my project I have a layer linked to an external WMS server (provided by a local institution). The problem is that it is somewhat unreliable: it is down rather often. Is there something I can do to ...
1
vote
0answers
68 views

how to add polylines(routes from public transport) on postgresql(pgrouting) with GUI

After searching a several long time... i decide to ask here for help, im currently using ubuntu 12.04(because of compatibility) with postgresql 9.1, postgis2, pgrouting2 and qgis2.2 i need ...
1
vote
1answer
55 views

How does the tolerance influence QgsGraphBuilder and tieing of points?

I am developing a script which uses OpenStreetMap data to calculate the distance (over the road network) between each building and the nearest hospital. To do this, I mainly follow the official ...
0
votes
1answer
45 views

Analysing a network distance to two or more points using GRASS or QGIS

I am doing a piece of analysis work looking at distances along a network in GRASS. Most of the analysis involves finding which parts of the network are within 600m of a series of points. GRASS does ...
1
vote
1answer
164 views

Read and Export OSM Road Data as a Network of Road Segments [Adjacency Matrices]

I wish to extract from an OSM file a road network, and export it as an array (adjacency matrix) where the nodes are the road intersections and the edges represent the road segments. I don't want to ...
1
vote
0answers
100 views

Drawing a road network: offsetting overlapping lines (directed graph)

Say I have a road network defined by a table, indicating, for each arc, its ID, and its head and tail node. In other words, my network is defined as a directed graph. For example, we have two points, ...
0
votes
0answers
24 views

How to turn this into a routable network that works with pgRouting? [duplicate]

I'm only asking again since I didn't get any answer and I'm still stuck here... I updated my last question with more info, but it wasn't answered. When I draw a line with snapping enabled and try to ...
1
vote
1answer
64 views

Creating a point buffer along a road network [duplicate]

I have a road network and have added points indicating fire hall locations. How would i go about creating buffers on those points following the road line. The result am i looking for would create a ...
6
votes
4answers
198 views

Automatic matching of two street networks

I'm faced with the problem of matching two street networks. I have these two differently sourced networks. The links in each network can be segmented, i.e. there is not necessarily a single whole link ...
1
vote
1answer
86 views

Find directly joined neighbour points using a different line layer in QGIS

I have two layers of data: A set of points showing every significant point on the UK rail network (Network Rail Stanoxes). These are a mixture of stations, junctions, timing points and signals. An ...
2
votes
0answers
206 views

How to specify cost attributes for network analysis in QGIS using the GRASS plugin?

I have a road dataset with information about the length, speed and drivetime for each segment. I use QGIS 1.9 with the GRASS plugin to do different types of network analysis, but how do I set up the ...
3
votes
1answer
169 views

Map walking distance/time from transit stops

I'm working in QGIS and would like to show how far from a bus stop a pedestrian could walk along the street network in any direction for a specified set of walking times (5,10,20 mins etc). I have my ...
0
votes
0answers
152 views

How to Calculate Shortest Path Routes for Multiple Start and End Points?

I'm new to QGIS and was wondering, is there a way to calculate shortest paths along roads for multiple sets of points? So basically what the roadgraph plugin does but for a series of start and end ...
1
vote
1answer
633 views

How to find the watershed area for each point in the river network using DEM?

Update#1: Thanks, Micha, I have followed your instruction and successfully use the modules in GRASS. I use r.watershed to get the basin raster and the drainage line: and I use r.water.outlet to get ...
8
votes
3answers
609 views

Howto setup and use a remote GIS workstation (QGIS,GRASS,PostGIS)?

I'm using QGIS (and sometimes GRASS and PostGIS) on my 2009 MacBookPro for my thesis project. I was wondering (during an endless batch generalizing in QGIS) if I can set up a server so I can work from ...
2
votes
1answer
192 views

How to join nodes to network lines ( and not the other points)

I'm trying to do a shortest path analysis on my network. In order to prepare the network and attach polygon centroids to the roads, I used GRASS' V.NET operation=connect. the problem with this ...
2
votes
3answers
193 views

How to route railcars along railroads?

I'm very new to the world of GIS, but I'm learning a great deal from this site, as well as others. I fell like this should be 'easy' but I need to be pointed in the right direction. I'm trying to ...
3
votes
1answer
547 views

How to get the distances (shortest path) between all pairs of points in the river network?

I have 2 vector shapefiles (one line, one point), and I have tried at least 4 ways to try to get the distance matrix at one time (and most concern the directions of each river segment) quantum ...
1
vote
1answer
250 views

How to create routable network by pgrouting with assign_vertex_id?

I'm trying to create the routable network as per http://underdark.wordpress.com/2011/02/07/a-beginners-guide-to-pgrouting/and use assign_vertex_id. Do I still need to create the node table? How would ...
1
vote
1answer
335 views

Creating routable network table in PostGIS

I am trying to create the routable network table, as per http://underdark.wordpress.com/2011/02/07/a-beginners-guide-to-pgrouting/. Everytime I do it in PostGIS extension, QGIS crashes. The area is no ...
5
votes
4answers
885 views

How to find dead-ends in a road network

I'm trying to remove all the dead-end roads in a road dataset (lines) that are less than 100m long. How do I identify roads that are dead-ends (no exit)? The 100m part is easy. I know how to use Arc ...
6
votes
2answers
1k views

How to calculate Network Service Areas in QGIS?

Is there any way in QGIS to apply service area buffers e.g if I have a point on a map I wish to show the service coverage of 1 mile, 2 mile, 3 mile, breaks using the road network?
2
votes
1answer
163 views

Visualizing KMZ network link in QGIS

Is it possible to open and visualize and kmz network link in QGIS. If so what are the setps involved? Thanks in advance Cheers
4
votes
1answer
737 views

Using QGIS calculate distance of point along a line

I have lots of points, and a road (lines) and I would like to calculate from point A to point B (the distance must route through the roads (lines). I found this QGIS calculate distance of point along ...
10
votes
5answers
2k 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 ...
6
votes
1answer
382 views

How to find the shortest path within a polygon? [closed]

I am trying to find a way to calculate the shortest path from one point to another without crossing the boundaries of a polygon. I would like to do it with QGIS as I do not have access to ArcGis. It ...
3
votes
3answers
604 views

Design fiberoptic network in QGIS?

I'm a GIS newbie trying to design a fiberoptic network in QGIS. What I'd ideally need is to draw lines on top of a map or orthophoto, assign a name/id to each line and a type. Get a list of all the ...
9
votes
4answers
2k views

How to connect lines in a network?

I have a shapefile of lines and another of polygons. When two or more lines intersect a polygon they should be connected (snapped), but sometimes during manual digitization this doesn't occur. I need ...
5
votes
1answer
431 views

Is there an open source tool to planarize graphs?

I read about the planarize function in ArcGIS, which seem to do exactly what I want. Is there a similar feature in QGIS or another free tool? I have a shapefile with various shapes intersecting each ...