Routing with Google is quite cool as the database/network is probably the best currently available. But the terms of services limit the possible usage. So what about OpenStreetMap? By figuring out how to use OSM for routing I found it much easier to get routes into QGIS with OSM compared to the Google way. Check it out….Prerequisites for Routing with OSM: Coordinates
Before we will have a look on the routing and getting the web response from OSM into QGIS we need to translate our start and end locations/addresses into coordinates. If you have point features you can simply add the geometry to the attribute table:Of course you also have access to the point coordinates using the PyQGIS commands
l=qgis.utils.iface.activeLayer() #for your activated point shapefileiterator = pl.getFeatures()for feature in iterator: geom = feature.geometry() print geom.asPoint()As we have all the coordinates we can move on to the routing.Routing with and Import from OSM
The University of Heidelberg owns a great routing platform. Furthermore they have an API for this nice little tool which is well described on the OSM wiki. We will use this API. The API will respond a XML document which then will be parsed into a line shapefile. So let’s start:
First let’s get the response into the Python console. We will start with the route from Oedheim (Germany) to Modautal. The above described solutions will give us the coordinates from the start and end point or our route:Oedheim 9.256506 49.240011Modautal 8.72083 49.7606We can use this coordinates already in the browser and open the following URL:http://openls.geog.uni-heidelberg.d...ays=false&noTollways=false&instructions=false
XML response from openrouteservice.org
How to do this in Python? We will use the requests module for getting the request and the build-in xml parser xml:import requestsfrom xml.etree import ElementTreeurl="http://openls.geog.uni-heidelberg.de/testing2015/route?Start=9.256506,49.240011&End=8.72083,49.7606&Via=&lang=de&distunit=KM&routepref=Fastest&avoidAreas=&useTMC=false&noMotorways=false&noTollways=false&instructions=false"response = requests.get(url)xml = ElementTree.fromstring(response.content)Now we just need to analyze the structure (take a look at the response in your browser) and we need to know that this sentence from the Etree documentation:
Google vs. OSM routing
Unfortunately we can’t rely on this project from the University Heidelberg:
Before we will have a look on the routing and getting the web response from OSM into QGIS we need to translate our start and end locations/addresses into coordinates. If you have point features you can simply add the geometry to the attribute table:Of course you also have access to the point coordinates using the PyQGIS commands
l=qgis.utils.iface.activeLayer() #for your activated point shapefileiterator = pl.getFeatures()for feature in iterator: geom = feature.geometry() print geom.asPoint()As we have all the coordinates we can move on to the routing.Routing with and Import from OSMThe University of Heidelberg owns a great routing platform. Furthermore they have an API for this nice little tool which is well described on the OSM wiki. We will use this API. The API will respond a XML document which then will be parsed into a line shapefile. So let’s start:
First let’s get the response into the Python console. We will start with the route from Oedheim (Germany) to Modautal. The above described solutions will give us the coordinates from the start and end point or our route:Oedheim 9.256506 49.240011Modautal 8.72083 49.7606We can use this coordinates already in the browser and open the following URL:http://openls.geog.uni-heidelberg.d...ays=false&noTollways=false&instructions=false
XML response from openrouteservice.orgHow to do this in Python? We will use the requests module for getting the request and the build-in xml parser xml:import requestsfrom xml.etree import ElementTreeurl="http://openls.geog.uni-heidelberg.de/testing2015/route?Start=9.256506,49.240011&End=8.72083,49.7606&Via=&lang=de&distunit=KM&routepref=Fastest&avoidAreas=&useTMC=false&noMotorways=false&noTollways=false&instructions=false"response = requests.get(url)xml = ElementTree.fromstring(response.content)Now we just need to analyze the structure (take a look at the response in your browser) and we need to know that this sentence from the Etree documentation:
Children are nested, and we can access specific child nodes by index: root[0][1].text
Keeping this in mind we can easily iterate over the point coordinates of the route and add them as vertices of a line shapefile:from PyQt4.QtCore import QVariantlayer = QgsVectorLayer('LineString', 'route_OSM', "memory") pr = layer.dataProvider() pr.addAttributes([QgsField("attribution", QVariant.String)])layer.updateFields()fet = QgsFeature() seg=[]for i in range(0,len(xml[1][0][1][0])): seg.append(QgsPoint(float(str.split(xml[1][0][1][0].text)[0]),float(str.split(xml[1][0][1][0].text)[1]))) fet.setGeometry(QgsGeometry.fromPolyline(seg)) fet.setAttributes(["route provided by openrouteservice.org"])pr.addFeatures([fet])layer.updateExtents() #update it QgsMapLayerRegistry.instance().addMapLayer(layer)And now let’s compare:
Google vs. OSM routingUnfortunately we can’t rely on this project from the University Heidelberg:
Description: Through the OpenLS interface requests can be generated to the appropriate services without further query limitations. The offered API’s are only valid for ‘ one ‘ year.In case you plan a long-term use of the interfaces within your projects or high volume or for commercial applications , please contact openrouteservice AT geog.uni-heidelberg.de
Nevertheless: Download the example and alter it for your needs.The post Routing in QGIS… with OSM appeared first on Digital Geography.