GIS Blog

Map Services for the Masses

Here we look at adding web services to a map in Pro.

If you live in Selwyn, it’s nice to know that you can go to the web and have a look at the district plan – local government in action.  You can go a step further and look at the maps in their Eplan webmap:

Click on what you see on the map and you’ll get some more information in a window off to the side:

Handy, yes?  Hopefully many of you would look this and think, hmmm, feels kinda like GIS.  And you’d be right!  These maps are coming off of ECan’s servers and let loose on the world for all to see.  A number of people might look at this and also say that there’s some useful stuff in here for my analysis.  Wouldn’t it be nice to able to add this to my GIS map?  Fear not – it’s relatively easy (once you know how) but it does come with a few very big caveats.  First we’ll talk about how to get this on your map and then we’ll talk about the limitations.

These maps are out in the world as web services – essentially dumb images of GIS data that can be streamed over the web and used in browsers, much like what you see in Google Maps or Google Earth or just about any webmap you come across.  What we need to know to add these to a map in Pro is their URL, or, more precisely, the URL of the server they live on.  You’d be excused for not know this, but it is:

https://gis.ecan.govt.nz/arcgis/rest/services

Being a URL, you could plug this into a browser and this is what you’ll see (go on…click on it, I dare  you):

Those folders hold details on different web services available.  Basically, anything you see on Canterbury Maps is coming from here.  Looking in the Selwyn_DC folder we see:

And there’s our district plan as a map service.  Clicking on that, we can see all the layers available in this service:

That’s a lotta stuff!  As we’ll see in a bit, we can add all these at one time or as individual layers.  Now let’s get these on a map.

In Pro, go the Insert tab and look for Connections:   .  There are a lot of options available here:

To add these layers we want to choose “New ArcGIS Server” – there are other kinds of services that we need to choose those other options for but ECan uses an ArcGIS Server for their data so we’ll go with that.

For the Server URL we can use the one up above – no need for a username and password:

When OK is clicked we get a new Servers folder and connection in the Catalog pane:

I can expand the connection and there are all the folders we saw in the browser above:

Any and all can be previewed in the Catalog View (these layers are from the Public folder):

Anything in these folders can be added to your map.  We’ve been talking about the Selwyn District Plan thus far, so inside the Selwyn_DC folder is the plan and all its sublayers:

I could add individual sublayers but I’ll just add them all by dragging the top level SDC_DistrictPlan onto my map:

(I could also add this from the Map tab > Add Data > Servers > services on gis.ecan.govt.nz.ags)

Once on the map, most of they layers are greyed out but as I zoom in they become visible – their visibility is tied to the scale of the map:

I can click on features and get pop up windows with more details.  Handy, but wait, here come the caveats.

As noted above, these are dumb images of GIS data – they come precooked with symbology that we can’t change, other than adjusting their transparency.

We can’t access their attribute tables except though pop ups.

Most importantly, we can’t use this layers for analysis – they can’t be used as inputs to tools.  It is possible to set up layers so they can be used this way, but they have to be configured properly.  They can also be set up to be edited by GIS users or people using webmaps.  But not these ones.

The best we can hope for on these is to use them as basemaps upon which we can digitise our own data.  There’s a chance the data may be available on Canterbury Maps’ Open Data site for download, but no guarantee.

So, on the one hand, it’s great that we can add these layers onto our maps, but a bit of a bummer we can’t use them for analysis.  Nonetheless, good on Selwyn District Council for making these available and double (nay, triple) good on ECan for making all this possible.  Several other district plans are available through this URL plus a wide range of other interesting layers (e.g. the Public folder).  Imagery can be had at https://gisbasemap.ecan.govt.nz/arcgis/rest/services – too many for me to show in one image:

Once you know where to look there are a lot of these services available.  To finish this off, consider the basemaps built into ArcGIS that we change to show different background.  These are web services themselves.  If you want to see where they come from, go to:

http://services.arcgisonline.co.nz/ArcGIS/rest/services/

Each of the NZ specific basemaps can be found in one of those folders.  For instance, the NZ Community Basemap is in the Generic folder:

To see it, click on the Generic/newzealand link:

Lots of gobbeldy gook – but if you click on View In: ArcGIS Javascript you’ll see the basemap as we usually see it inside Pro:

(To be fair, I had to zoom out and pan to see this bit, but it’s there.)  The global scale basemaps live on servers in California.

There are a lot more technical details sitting underneath this and I’ve totally avoided talking about wonky things like REST endpoints, but suffice it to say that there is a huge range of services like these that can be added to your maps, so long as 1) you know they’re out there, 2) you’re happy to not be using them for analysis and 3) you know the URL they live at.  But that’s a map service for another time.

C

• 02/06/2021


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