Have it Both Ways

Connecting to and Editing ArcGIS Feature Services in QGIS

Housekeeping

The purpose of this talk is not necessarily to promote one software over another, but rather one in addition to the other.

But really, Pro and Q are totally different tools that happen to have a healthy amount of overlap.

The stuff in the middle, that’s really your call. But the stuff on the edges, things that only one of the tools can do? That’s worth paying for!

If your org is like mine, you’re probably already an Esri customer, and you probably have good reasons to be. For Kendall County, it’s the parcel fabric.

Being FOSS, the only thing stopping you from testing the waters with Q is a bit of time and disk space.

What I really want from this presentation is

1. To expose you to some of the neat capabilities of QGIS.
2. To demonstrate that “work with AGOL / Portal layers” is in the middle of the venn diagram

It’s ultimately not for me to say which tool is best suited to your particular workflows. But how will you know which tool is best unless you get familiar with them?

Worth Paying For?

(Soapbox Warning)

Esri Legal: Open Source Acknowledgements

At Kendall, we put our money where our mouth is. Just because it’s free to get doesn’t mean it’s free to make.

As of 2024, Kendall is the only US-based government supporting QGIS, and indeed one of the few government entities globally to do so. Our supporter badge will update to say 2024 when we renew later in February.

Overview

1. Why you should try it
2. A brief tour of QGIS
3. How to make the connection
4. Things you can do

Reasons Why

You’re working with AGOL / Portal and…

• Lots of editors, not a lot of budget
• Distributed workforce
• File interoperability
• You’re not running Windows
• You prefer QGIS
• You want to use advanced capabilities that Q offers

A Tour!

Connect to a REST Directory (Anonymous)

Generally not what you’ll use for editing. This will let you access any public layers in a given server. Great for when you need to pull data from another organization.

Via Browser Panel

Via Data Source Manager

New Connection Dialog

Let’s use the US Census TIGERweb as our example.

• name: TIGERweb
• url: https://tigerweb.geo.census.gov/arcgis/rest/services

No other settings need to be configured.

Demonstration!

• name: TIGERweb
• url: https://tigerweb.geo.census.gov/arcgis/rest/services

Connect to AGOL / Portal (Authenticated)

Credit where it’s due

The steps discussed here come from the invaluable guide at North Road.

AGOL / Portal: Add and Register an App

1. My Content → Add Item → Application
2. Register application with local redirect URLs
3. Get the Client ID and Client Secret

QGIS: Create an Authentication

1. Options → Settings → Authentication
2. Fill in the appropriate URLs (see previously linked article)
3. Enter the ClientID and Client Secret from your registered app

QGIS: Create Authenticated Connection

1. Put in the REST URL as before
2. Fill in the Community and Content endpoints
3. Include the authentication credentials

Browse and Add Services

Anonymous vs Authenticated

Add from Browser Panel

Good for simple adding of layers, but lacks options.

Add from Data Source Manager

1. Click “connect” to view services
2. Search / filter by service name
3. Select service from list
4. Set spatial filter on service
5. For image services, request images be encoded in specific format
6. Add with an attribute-based filter ¹
7. Add layer

The spatial filter and image formats can only be configured from this view.

1. Can be added later, too

Demonstration!

The Fun Stuff

Editing

Here’s a private layer in my AGOL account. It has editing enabled, but is not accessible to other users.

There’s a public, non-editable view layer, too, with a corresponding map.

Show:

• Processing algorithms in place
• Editing attributes
• Split, merge, mess with rings
• Add and delete features

Virtual Layers

• Make query layers from basically anything
• Fancy SQL stuff ¹
• Spatial SQL stuff

Examples:

• Polling places and precincts. Want to have an ascending series of letters for each polling place, per township. Don’t want a new field for this. SQL, we can use ROW_NUMBER and CHAR to get those letters, partitioning by township, which we join in from the precincts.
• Polling places atlas. We want one page per township. Let’s pretend we don’t have a township layer, or that we want to be certain that the precincts and townships are aligned. We can use ST_UNION and GROUP BY to dissolve the precincts on their township field.
• Buffered Points: want to have a series of buffers around some points for further analysis. Points layer is constantly being updated, don’t want to re-run buffer every time.

1. SQLite / Spatialite

Virtual Fields

• Casting / converting values
• Interact with other features / layers
• Works on layers you’re not allowed to modify

Examples:

• A table with lots of address fields, I just want a “mailing address” field that cuts out all the nulls and stuff.
• A table with a field that should be multiple, I want the information split out.

Geometry Generator Symbology

• On-the-fly generalization, buffering, etc
• “Cast” the geometry as a different type
• Can be used in conjunction with other symbology types
• Just plain old weird stuff

make_line(
    array_foreach(
        geometries_to_array(nodes_to_points($geometry)),
        translate(@element, randf(-1,1), randf(-1,1))
    )
)

Data Defined Overrides Everywhere

• Too much to really go over!
• Doesn’t need to be from the same feature or layer
• Other variables
  • Cursor position
  • Atlas feature
  • System settings

Atlases, Variables, Inter-Layer Expressions

• Sort of like Map Series, but not
• What if you wanted the series map extents defined by something other than the main feature?

I’ve got the TIGERweb townships and counties for NE IL added. I want an atlas of maps per township, but each page should show the parent county.

1. Check out the Atlas setting in the layout.
2. Data defined overrides for extents
3. @margin variable on map item
4. @atlas_feature variable in expressions

Questions?

Be in Touch!

josh@jcarlson.page

https://jcarlson.page

@jcarlson@mapstodon.space