An interconnected set of points and lines that represent possible routes from one location to another, OR in computing, a group of computers connected in order to share software, data, and peripheral devices, as in a local or wide area network.

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37
votes
7answers
10k views

Creating drive time polygons using open source tools

Is anyone using open source tools and/or data to generate drive time polygons that radiate out from a given location? For example, I have used ESRI products like Network Analyst and Business Analyst ...
29
votes
8answers
3k views

Representation of network flows

This is a sample transportation network flow I've done a year ago based on 26 zones. For a project I'm working on now, I need to represent the flows over 1,000 zones with directionality. Any ...
23
votes
10answers
4k views

Alternatives to pgRouting

I was wondering if there are any alternatives to pgRouting tools. Thinking about it for a bit, I think the only alternative is to use R or RPY to do the analysis. Basically I'm trying to solve ...
20
votes
7answers
2k views

Alternatives to Network Analyst

I'm not sure how reasonable this question even is, but it leaves me no less curious after a bit of searching. If I am looking to build a network based on road features and attributes, is Network ...
18
votes
5answers
978 views

How to simplify a routable network?

I have a network graph that I need to simplify in the sense of reducing the number of edges. The idea would be to merge nodes that are located close together and remove the connecting short edges. ...
13
votes
6answers
1k views

What is the best method of visualizing a network on a map?

I have several hundred geo-referenced data points, and the relationships from that point, to other points. I'm trying to figure out the best way of visualizing this on an interactive map (possibly ...
12
votes
6answers
1k views

What's an efficient way of detecting road junctions on a map?

I may receive maps from any source for my project, and for the C++ algorithm I'm making, it's imperative for the algorithm to know where road junctions (nodes where more than two road segments meet) ...
12
votes
3answers
689 views

PgRouting - How to clip links when reaching max costs?

I have a polyline shapefile representing a road network and a second shapefile containing points. I would like to use PostGIS (presumably PgRouting) to identify sub-networks or service areas radiating ...
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 ...
11
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 ...
10
votes
5answers
4k views

Which tools and methods can be used to create isochrones?

I'd like to get an idea for what's involved in creating isochrones for a series of sites, with a reasonable degree of accuracy to the estimates. A general outline would be great, though my scenario ...
9
votes
1answer
2k views

Difference between network dataset and geometric network

In ArcGIS, what is the difference between a "network dataset" and a "geometric network"? Are there differences with what can be done with each?
9
votes
2answers
442 views

Generate near table for x number of neighbours using arcpy

There are 3 likely scenerios that I am trying to capture near distances for: An interchange subway station, which has 2 or more neighboring stations. That is, the station in question connects 2 or ...
9
votes
1answer
179 views

How to create a branch network from several input points to an unique outlet in minimizing the distances?

I am searching a way to "hydrologically" connect upstream points to a unique downstream outlet by creating an optimized stream network as pictured below... The cummulated lenght of the stream lines ...
8
votes
3answers
787 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 ...
8
votes
3answers
2k views

How to emulate Google Maps driving directions using pgRouting?

Would like to emulate google maps' driving directions functionality but use pgRouting instead. google's data over the project area & scale is quite a bit off so we want to use our own transport ...
8
votes
2answers
192 views

Spatial Network Cleaning

Data used to create a network from has special considerations when cleaning, as minor spatial errors can lead to major bugs in connectivity. What techniques could be considered best practice for ...
8
votes
1answer
248 views

Large survey on unconnected underground networks

We (read I) are currently surveying all the stormwater pits and pipes in our shire, and have run into a few issue with handling unknown network connections. The problem is that a lot of our network ...
7
votes
1answer
230 views

Do ModelBuilder or Geoprocessing tasks run slower if screen locked?

Is it true if you are running ModelBuilder or a geoprocessing task on a large raster\vector dataset then locking the computer would that cause the ModelBuilder or any geoprocessing to run slower? Is ...
7
votes
3answers
2k views

How to compare 2 polyline datasets?

I have a network data set for footpaths which I have generated through the collation of path networks from a variety of sources. I want to compare this with another dataset which also contains a path ...
7
votes
4answers
245 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 ...
7
votes
2answers
551 views

Conflating Two Network Datasets in ArcGIS

I am looking to merge two network datasets in ArcGIS 10.0. I have an ArcInfo license and have trawled this forum but am looking for some clarification. I want to merge two road networks but only make ...
6
votes
4answers
1k 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
2k 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?
6
votes
2answers
811 views

How do I select only those features, that are connected?

I have a polygon layer of water reservoirs and a polyline layer of canals. In my data, some canals are originating from reservoirs, and leading to other canals. On the other hand there are some ...
6
votes
2answers
227 views

How can I turn a vector layer into a graph G = (V, E)?

I have a number of rail networks, in the form of shapefiles of the "line" type. I want to turn them into a more abstract graph format, i.e. the kind with vertices and edges, not chart-type graphs. ...
6
votes
2answers
2k views

Segment road network line shapefile into new equal length segments line shapefile

I would like to subdivide a road network for an entire state into segments of equal length. So, Highway X would be divided into 0.5 mile segments, with a record for each segment, and Highway Y would ...
6
votes
3answers
952 views

Find a proper path between two nodes in a grid

This question is about finding a proper path (route) between two nodes (P,Q) in a grid (i.e., graph, network, ...). In our concept, we define a path proper (nice) if it is the most similar* to the ...
6
votes
1answer
414 views

calculate slope for a road network

I am working on a road network for routing operations using postgis and QGIS. I am new to both of these tools and need to calculate the slope for each edge (by retrieving the Z value for the start ...
6
votes
2answers
333 views

How can I improve the speed at which QGIS 2.4 handles network data? (Seems much slower than 2.2 - even with small datasets)

I recently downloaded and installed QGIS 2.4 Chugiak on a Windows 7 64-bit machine with a quad core processor and 8GB RAM. I'm having a few problems using datasets of all sizes from a network drive - ...
6
votes
1answer
422 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 ...
5
votes
3answers
480 views

Tracing up a stream network & tabulating attributes of polygons it passes through

I have an ArcGIS question that is either very easy or impossible (my favorite kind). I am somewhat inexperienced when it comes to dealing with network analysis, so maybe I'm missing something major ...
5
votes
1answer
463 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 ...
5
votes
2answers
1k views

Are there any open source network analysis tools?

A researcher in my field* recently created an "Urban Network Toolbox", an ArcGIS extension built upon Network Analyst. It calculates a number of measures on urban networks, such as betweenness and ...
5
votes
1answer
891 views

How to generate a point distance matrix using shortest network distance?

My problem is as follows. To start with, I have the following spatial datasets: A road network; 13,000 odd point locations representing populated localities (ie places where people live); Service ...
5
votes
1answer
1k 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
646 views

Geometric Network - Listening to network feature connection changes in the IObjectClassEvents::OnChange event

I need to be able to tell when a particular type of feature, that participates in a geometric network, is having its geometry automatically modified due to the geometric network. What i mean is that ...
5
votes
2answers
446 views

How to sum an attribute of a feature in a network along a route? (ArcGIS Network Analyst)

In the walking network that a friend and I are creating, we want to calculate an overall safety rating for each route. Each segment of our walking network has a certain safety value. We have ...
4
votes
2answers
648 views

How to find the watershed for each outlet point and sum values within it?

I have the following files to work with: Stream network of a basin; Outlet points for each segment* of the network and Points which represent water withdrawals along of the stream, which are not ...
4
votes
2answers
534 views

Which are the best open source tools/solutions for digitizing road networks?

I was thinking on tools/plugins for QGIS, but other good suggestions are welcome.
4
votes
1answer
1k views

How to find network distances between two sets of origins and destinations?

I'm learning how to use Network Analyst, and I'm not entirely sure what to do (or search for). My objective is to measure the nearest distance from the red circles to the blue circles along a road ...
4
votes
1answer
93 views

What are the existing datasets of world maritime routes?

I have a list of cargo ports of all over the world and need to show some port-to-port trips on a map, and also to compute lengths of these trips. For that, I need a dataset of actual maritime routes ...
4
votes
2answers
57 views

How do I create blocks from a road network?

I have a road network and for every enclosed area within the network I want to create a polygon that represents that area. How does one do this?
4
votes
1answer
738 views

Assigning points to their respective Reaches using Stream Gradient?

This is a continuation of the question I initially posed here. Also, I've attached a shapefile on my Drop Box account here. I'm trying to break a stream network up into 100m reaches, assigning ...
4
votes
2answers
181 views

Transportation representation Standard on roads

Is there a GIS standard to display transportation specific information in GIS databases. The information I'm interested in are: Road Directionality Center turning lanes Ramps / Bridges / Over or ...
4
votes
2answers
135 views

How to connect points (bus stops), which don't lie on the lines (LINESTRING), to a network?

I need to connect bus stops (points) to a network layer (OSM data). These bus stops do not lie directly on the lines (see screenshot) nor should their location be moved. I use PostGIS, pgrouting and ...
4
votes
1answer
822 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 ...
4
votes
1answer
534 views

Is there an open source tool for both road network analysis and geocoding?

Is there any one open source software package that can perform both road network analysis and geocoding?
4
votes
1answer
119 views

PostGIS table to network analysis

I use PostGIS 2.0 and Python API (GeoAlchemy) to work with it. I want to convert topological informations (points, lines, faces) from PostGIS tables to topological network (points, lines) to study it ...
4
votes
1answer
152 views

How do you define rail network branch geocodes

As per the attached document I'm trying to define a rail network by providing geocodes for each rail stop, how would I define a 'stop' as a junction for a branch in the network without having to ...