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.
30
votes
7answers
5k 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 ...
22
votes
7answers
2k 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 ...
18
votes
8answers
3k 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 ...
15
votes
1answer
195 views
Are there any standards or common practices for performing a network analysis for emergency response?
I am working on a project using Network Analyst to determine official emergency response zones for fire departments. The shape of each zone will be determined by the network (at least 1 department ...
14
votes
3answers
1k views
Network Analyst - Is it the only choice?
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 ...
12
votes
4answers
979 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
986 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
579 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 ...
10
votes
3answers
538 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.
...
9
votes
3answers
1k 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 ...
8
votes
1answer
1k 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?
8
votes
3answers
1k 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
263 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 ...
8
votes
1answer
90 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
1answer
234 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
3answers
199 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 ...
7
votes
5answers
2k 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 ...
7
votes
3answers
905 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
1answer
158 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
2answers
389 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
381 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
121 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
1k 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
583 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
225 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
5answers
714 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 ...
5
votes
1answer
325 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
793 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
221 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
435 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
368 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 ...
5
votes
1answer
307 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 ...
4
votes
4answers
191 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 ...
4
votes
3answers
367 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
1answer
49 views
How to find the Closest Facility (euclidean distance)?
I have some facilities and incidents, and I want to find the closest facility for each incident. I've done it via Network Analyst (with a network dataset) but I'm wondering if you can do it with just ...
4
votes
2answers
389 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
580 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
2answers
401 views
How to include polygons as part of a network for Network Analyst (ArcMap)?
I am creating a pedestrian walking network of a downtown area. I am digitizing line segments for paths and sidewalks, but I need to incorporate parking lots into my analysis. So far, I have been ...
4
votes
1answer
556 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 ...
4
votes
2answers
146 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
1answer
399 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
476 views
Stream Gradient - Assigning points to their respective Reaches
This is a continuation of the question I initially posed here.
Also, I've attached a shapefile on my db account here.
I'm trying to break a stream network up into 100m reaches, assigning elevation ...
4
votes
1answer
114 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 ...
4
votes
0answers
428 views
How to use Route Task in Network analysis tools
I am using esri network analysis tool and I just want to draw the path between two clicked point on the map (by using route task)
I use the example code block in the following link
...
3
votes
2answers
344 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 ...
3
votes
2answers
142 views
Can GRASS v.net.iso split between nodes?
Can GRASS's v.net.iso module split networks between nodes on the network, i.e., if I am finding the area within a cost of 400, and there is a line segment with a cost of 800 leaving the center node, ...
3
votes
2answers
226 views
Can ArcHydro Tools be used on a network in an SDE enterprise geodatabase?
Most of the documentation for ArcHydro Tools discusses their use on data in ESRI's personal and file geodatabases. Is it possible to use ArcHydro Tools to set network flow direction on a networked ...
3
votes
2answers
134 views
Get the junction id for the roads in a network dataset
I have a network dataset with roads and junctions. I am wondering what class I can use in arcpy to extract FromJunctionId and the ToJunctionId for each road segment in the network dataset.
Thanks.
3
votes
2answers
119 views
LRS schema error in Oracle SDO_NET when validating network
I have a problem with the Oracle Spatial Network package. I'm creating NODE, LINK and PATH based on LRS. When I try the call:
SELECT SDO_NET.VALIDATE_NETWORK('network_tracking') FROM DUAL
then I ...
3
votes
2answers
79 views
Using the ArcGIS Local Routing Tool . . geoprocessing in the runtime
When I create a model in ArcGIS using the Network Analyst Tools, I am able to create Locations and make the Route Layer and Solve. However, I need to be able to add barriers as well as locations, ...
