Canterburymaps.govt.nz and Web Services
The Canterbury councils recently got together (gasp!) to produce a map portal for the whole region. This post covers that as well as brings up how web services can be used to access publicly available data.
It may sound hard to believe, but the district, city and regional councils got together recently and decided to work together to produce Canterbury Maps, a mapping portal for the whole region. You can go there and select from several maps, including liquefaction susceptibility, library locations, swimming water quality, and a range of other more generic basemaps.
Though it might not be apparent from such easy access, I can attest to the Herculean efforts that went into this. Currently, there are no common standards for data within local government, so each council tends to have its own way of managing, storing, and providing data, though there’s no requirement of any commonality in what data are collected nor which attributes are stored. All district councils would have data on, say, stormwater infrastructure, but there’s nothing that requires them to do it all in the same way. And when these data need to come together in a common environment, well, they might as well be in different languages. But our friends at the councils have joined hands, sung Kumbaya, my lord, Kumbaya, and we now have access to the consistent data across the region. This is an offshoot of ECan’s GIS data viewer and was largely coordinated by them, with much pulling of hair and gnashing of teeth, I might add.
This is interesting for a number of reasons. First, this is about making publicly funded data publicly available. Second, it’s a bit of an insight into where things are going GIS-wise. We’re all probably used to using something like Google Maps, or Open Street Map, or any number of on-line mapping applications (e.g. MapMyRun). These are putting the power of GIS into people’s own hands and freeing them from the tyranny of having to have ArcGIS loaded on their computer. Internet mapping is certainly the way many organisations are going as a way of making their data available to anyone with a browser (ourselves included). For instance, I’ve been working with a colleague at Otago, who doesn’t know very much about GIS (and is quite happy about that, thank you very much). An easy way for me to share the results of my analysis is to make a map available over the web (this is some work we’ve been doing around adolescent smoking and access to tobacco outlets near schools):
Now she can easily see the map without having to sit through one of my courses by going here.
But this does have its limitations. While it’s great to be able to see all those data on Canterbury Maps, that’s all you can do with them. What you’re actually seeing in your browser is an IMAGE of the data rather than the data themselves. You can’t add them onto a map or do any analysis with them (unless the website is set up to do this – that’s another post). And that’s where web services come in. Just as you can send an image over the web, you can also make a service available which is a connection to the data on someone else’s server. For example, ECan has a data layer of bus routes which you can no doubt find on Canterbury Maps. But they also have the same data available as a web service which you can add to an ArcMap map and use as if it were sitting on your hard drive. Here’s how that works:
Connecting to the ECan Web Services
First you need to set up a connection to the right server and that requires knowing the web address, or URL. (The rest of this post is pretty ArcGIS-centric – apologies.) If you up open up the Add Data dialogue, and get up to the top level, you’ll see an entry towards the bottom called “GIS Servers”:
Double-click that and go to “Add ArcGIS Server”. At the next window choose “Use GIS Services” and then “Next” The Server URL is “http://gis.ecan.govt.nz/arcgis/rest/services” (copy and paste that if you like) and you don’t need a user name or password:
Once you click “Finish” you’ll see a new entry under GIS Servers (I’ve got a few extra in mine…):
Double-click on that entry and you’ve got access to their public services, including aerial photos, topo maps, and, in the Public folder, Bus_Routes,which can be added to a map in ArcMap:
I can add my own data into this map and treat it as if it lived locally.
Now this is a step up from using a map viewer in a browser – these are data! Mind you, under the bonnet, you’re still only getting an IMAGE of the data (as a PNG or a JPG likely) but now you can meld these services in to create your own maps and, if they’ve been set up correctly, you can even get a live feed of the data (though there are some security issues around that usually) with which you can do analysis.
And ECan’s not the only one. Here are some increasingly useful web services you might like to try yourselves:
- http://maps.cera.govt.nz/arcgis/rest/services – the CERA folder has a lot of layers related to the rebuild
- http://geoportal.doc.govt.nz/arcgis/rest/services – DOC related layers (area boundaries, campsites, marine reserves, and lots more)
- http://arcgisonline.co.nz/arcgis/rest/services – generic layers from Eagle Technology. A good general basemap can be found in the Generic folder, while Census data are in the STATS folder)
A good way to figure out what services are available is to connect to a server from ArcCatalog and browse the services there, rather than adding everything to an ArcMap map.
You may have noted in one of the images above one “gis.lincoln.ac.nz”. This is our very own GIS server and is being used increasingly for getting maps and data out there, though I’ll have to say more about that in another post. Happy browsing!