Module 5: Working with networks

From ObjectVision

(Difference between revisions)
Jump to: navigation, search
Line 25: Line 25:
 +
===''[[Module 6: Doing land-use allocation| Go to previous module: Module 6: Doing land-use allocation]]''===
===''[[Module 6: Doing land-use allocation| Go to next module: Module 6: Doing land-use allocation]]''===
===''[[Module 6: Doing land-use allocation| Go to next module: Module 6: Doing land-use allocation]]''===

Revision as of 11:47, 27 July 2020

THIS IS WORK IN PROGRESS

Preparing a network

In this module we will use the OpenStreetMap network to calculate travel times between sets of points. However, first we must prepare the network since the downloaded OSM is just a set of lines with a typology. We must make sure that the network is connected and we must connect the origin and destination point sets to the network. For this purpose we use a script that is quite extensive but also necessary.

First download the network configuration here:

For this example we will calculate the traveltime to the nearest trainstations from each postcode-4 point. So in the container SourceData we have the trainstation points and the postcode-4 points.

In the container Analysis/NetworkDist we see 'org' and 'dest'

Those are simply redirections to origin and destination domain:

unit<uint32> org    := /SourceData/Shapefile_PointData_PC4;
unit<uint32> dest   := /SourceData/Shapefile_PointData_Stations;

In the all the subitems in this container when you refer to org it will use this specified org. So in case you will change the origin set, you'll only have to change this once!

Then there is the container NetwerkSpec, in here the actual network is created, amended and thus prepared for analysis.

The actual analysis is done in the attribute 'OD_Traveltime', here the Dijkstra algoritm is specificied with a couple of arguments. In this case a string with some settings, followed by 4 arguments seperated by a comma. The first three are always required, no matter which settings you use: impedance, F1 and F2. That is the impedance (traveltime in seconds) over a link (a connection between two points), and the F1 and F2 are the beginning and endpoint of said link. And in this case there is 'nr'.



Go to previous module: Module 6: Doing land-use allocation

Go to next module: Module 6: Doing land-use allocation

Personal tools