# Tag Info

17

You should be able to use the Arrow At End symbol from the Symbol Selector to show the digitised direction of polylines.

14

The purpose of that box is to control how far generated polygons will extend beyond the outside edges of the network. Consider a dense grid of streets as in a city. Service areas for facilities near the edge of the network may extend well beyond the range of your network with high enough break values. You are not concerned with areas beyond 'city limits', ...

11

Since you are on ArcGIS, here it goes.. Skills: I suggest starting with learning basics of Network Analyst (further NA). It is impossible to get started preparing the data for network analysis withouth understanding of the basics of the GIS routing and network analysis theory (graphs, edges, junctions, cost, algorithms). Industry: a good place to start is ...

10

Both are just different names for the same thing. You can see this by using the is operator: arcpy.na.CopyTraversedSourceFeatures is arcpy.CopyTraversedSourceFeatures_na will return: True Which tells you that both of these names point to the same object. Your best course of action is to pick one way of doing it in your scripts and stick with it. Just ...

9

Since you mentioned that are you doing network analysis, I recommend assigning the symbology for your road edges within the network dataset layer in the TOC instead. You are on ArcGIS 10.2, so here are the steps: Add the network dataset into the ArcMap TOC. Open the Layer Properties dialog box by double-clicking the network dataset layer in the ArcMap table ...

9

the grass algorithm v.net.alloc can produce the subnets - you can call it from the Processing toolbox (tested in QGIS 2.16) You'll need a point layer (for facilities) and a lines layer with costs (either time/length). It'll create a new line layer with a field called cat added, which will be the id of the nearest facility. Here's an example based on ...

7

This is an instance of a shortest path problem: given a set S of polygonal "obstacles" (considered as open point sets), a start point p, and an end point q, to find a shortest path from p to q that does not intersect the interior of S. Such problems are solved by first constructing the "visibility graph" of S. One first proves that any ...

7

Network Analyst uses a network of roads, because straight-line distance does not accurately represent the roads that a fire truck must drive on. This is especially true if there are geographic barriers (rivers or streams) or in a rural area with fewer roads. In contrast, flight time analysis would not use a network because planes or helicopters can travel ...

6

You cannot create a network dataset with arcpy at this time. Your option is to use ArcObjects. There is a Street Data Processing toolbox that is built on .NET by Esri (the source code is provided), which you might modify to meet your business workflows. A GP tool which is part of the toolbox creates a network dataset with certain user-defined parameters, so ...

6

If your facilities and incidents are both feature layers, and you only care about finding the closest (and not 2nd closest, 3rd closest, etc.) then you can just run Spatial Join. Set your incidents as the target_features, facilities as join_features, and closest as the match_option, and it will join the attributes of the nearest facility to each incident.

6

Your Network Dataset requires the Cost/Attribute in the Function Evaluator (when building your network) You can see here there are 4 types of attribute (Minutes will build your drive time analysis buffers) See Types of evaluators used by a network http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Types_of_evaluators_used_by_a_network/...

6

You should use the Reorder Stops To Find Optimal Route option. By default, a route traverses stops in the order you define. However, you can possibly shorten the route further by letting Network Analyst find the best order. It will account for a variety of variables, such as time windows. Another option is to preserve the origin and destination ...

6

As far as I know it's not possible to solve for alternate routes without some additional input or change to the analysis. In a network, given a particular impedance, there is only one shortest route between two points. As soon as you start looking for alternates without any additional input you've essentially removed the 'shortest' constraint and are back to ...

6

As an answer to both Uffe Kousgaard comments about "what the 18GB file contains" compared to a routable shapefile, and a possible answer to this question: You don't explicitly state it, but I guess you used the ArcGIS Editor for OpenStreetMap to convert your data. If not, I really recommend to have a look at it, as it contains a dedicated option to create ...

5

I think some of the answer depends on the layout of the road network, and this question might be worth posting on the Math Stack Exchange (https://math.stackexchange.com/) as it seems like a graph theory problem. I don't think this will be the optimal solution, but it might help get you closer. You could divide up the road network into natural regions, ...

5

My solution to this was kind of a kludge, but then I was doing a small class project working with a subset of one county's roads so the network wasn't that big and I didn't need to do it as a common task. I just ran a service area analysis with the time set large enough that in theory everything should be reachable. That highlighted everything that was ...

5

You could try the Identity tool, using your line features as the input, and polygons as the identity features: "When the Input Features are lines and the Identity Features are polygons, and the Keep relationships parameter is checked (relationship set to KEEP_RELATIONSHIPS), the output line feature class will have two additional fields, LEFT_poly and ...

5

A network dataset must reside within a feature dataset. A feature dataset can be created in either a file geodatabase (folder.gdb) or a personal geodatabase (filename.mdb). You can't create one in a shapefile, if that's what you mean by 'normal'. Note you'll need to add the street layer to the network dataset in order to build a network from it, and there ...

5

The ArcGIS network analyst extension needs a properly prepared network dataset (graph) for routing. Ordinary OpenStreetMap data sets are not routable because they are simple linestrings. Take a look at the OSM2NetwordDataset tool by Eva Peters. This tool creates a routable network dataset and takes turn restrictions (from OSM relations), oneway roads and ...

5

QGIS cannot convert OSM data into a routable graph. There are other tools which specialize on this task: osm2pgrouting open source osm2po free but not open source Both convert OSM data into a routable graph for import into PostGIS. From there, you can export in a format that you can feed into ArcGIS.

5

For QGIS, you could try the steps below. I used QGIS 2.12.3-Lyon and have a "road" line shapefile, the isolated road in the red circle is what we're trying to remove. Intersect your layer on itself (Vector > Geoprocessing Tools > Intersect): Load the Spatial Query plugin (you may need to download/install this from Plugins > Manage and Install Plugins): ...

5

In Network Analyst (NA), there is a concept of cost associated with traversing (that is, going through) a road link (edge). Such cost is calculated based on the direction in which a road link was digitized. In NA terms, it is referred to as FT and TF (from-to, to-from) directions. This means that the very same road link can have different cost associated ...

5

This looks like a Steiner tree problem. You'll need some programming to solve it. Picture below shows manually improved output of algorithm from networkX: and I think computing "flow" in this network will bring you even closer to near optimal solution: In this case SE student looks like a best candidate to start route. What you are doing will give you ...

4

Here is the step-by-step tutorial on how to calculate Service Areas. If you want to run the same analysis but several times providing multiple values for the operation, you might consider using the Make Service Area Layer and the Solve GP tools. There is a separate tutorial on this, too. If you need to build anything more advanced, consider using the ...

4

So here is what I would Find out: Is your License valid, and not expired? To see this go to Start>>ArcGIS>>Desktop Administrator and go to the Availability Section. You will see how many ArcGIS Network Analyst extension licenses are available on your License Server, and how many are free. It will also indicate the expiry date of the License. In ArcCatalog ...

4

This approach that @Allan Adair shown, it will definitely work, however in this case these road links you have restricted will become non-traversable. I approach this in another way - you usually do want to be able to go through such roads when travelling between points, you just don't want your routes to start and stop on them. So instead of restricting ...

4

I found the answer is due to python.exe having a limit of about 2GB. A solution is to Set 32bit Executable LARGEADDRESSAWARE Flag to True.

4

At the bottom of the help page on service area analysis that PolyGeo links to, there is a link to another help page: Algorithms used by the ArcGIS Network Analyst extension. From that help page: The Service Area solver is also based on Dijkstra's algorithm to traverse the network. Its goal is to return a subset of connected edge features such that ...

4

Esri's free ArcHydro Extension will do this ArcHydro page. Download from there or Download. Once installed, load shapefile. From ArcHydro select Attribute Tools > Generate From/To Node for Lines. This will generate FROM_Node & To_Node columns.

4

If you want Free (but you will have to do a lot more pre-processing) OS VectorMap™ District is available. https://www.ordnancesurvey.co.uk/opendatadownload/products.html For commercial rotatable data you have 3 options. Ordnance Survey - OS MasterMap® Integrated Transport Network™(ITN) http://www.ordnancesurvey.co.uk/business-and-government/products/itn-...

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