0
votes
0answers
18 views

problems using GRASS v.net and v.net.allpairs

I am using GRASS 6.4.3, and I am trying to use it to do network analysis. I have a line shapefile and a point shapefile, and here is my code(I take v.net.allpairs as my reference): v.net tc_bf25 ...
0
votes
0answers
9 views

problems using v.net.allpairs

I am using GRASS 6.4.3, and I am trying v.net.allpairs to do network analysis. I have a line shapefile and a point shapefile, and after I use v.net.allpairs, I type the command d.vect network, and I ...
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 ...
3
votes
2answers
115 views

Create network from shapefile without ArcGIS?

I want to perform shortest-path analysis on a network whose edges represent real-world roads and whose nodes are buildings or other locations. I have the shapefile for the area I'm interested in. ...
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 ...
0
votes
1answer
66 views

Adding additional nodes to network in Grass GIS

I have created a network in Grass GIS (using v.net, nodes option). I then want to "disrupt" the network (i.e., create some road blockages) and add in nodes to the new line ends where road blockages ...
0
votes
0answers
30 views

How to access layer attributes using grass network tools (v.net.iso)?

I had a quick look for a similar question, sorry if this is a duplicate. I am using GRASS 6.4.3 on windows - osgeo4w version I ran v.net.iso to split my road network by cost however when I try to ...
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 ...
0
votes
0answers
40 views

GRASS - Creating an Attribute Based on Driving Distance

Is it possible to calculate the driving distance for each node of one layer (fire stations) to each node of another (address points)? After doing so, I need to sort all of the distances from shortest ...
8
votes
3answers
610 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
96 views

Help with GRASS V.Net.Path

GRASS has extensive and brilliant documentation, but I still have a bit of trouble using v.net.path. in the example for shortest path, it says: " #Shortest path: ID as first number, then cat1 and ...
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 ...
0
votes
1answer
58 views

GRASS: Loss of data using v.net

I'm trying to build a network in GRASS in order to find the shortest path from any settlement out of 1120 (points), to one waste treatment facility out of 27 (points). I plan to use v.net.distance ...
1
vote
2answers
98 views

Error using Grass v.net

I'm trying to connect my network to a points layer with a threshold of 4500 meters. I have about 11000 or so entries in my polyline and about 24 in my points layer. I have alreday used v.distance, ...
5
votes
4answers
886 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 ...
1
vote
2answers
275 views

Network distance computations using GRASS

I'm an ArcGIS user who's interested in learning to use GRASS. Can anyone point out resources that will help me in learning how to obtain network distances between (1) residential locations (points) ...
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 ...
11
votes
3answers
742 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. ...
3
votes
2answers
175 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, ...