North River Geographic Systems Inc

Spatial Problem Solving

QGIS

Fed Geo Day 2020 June 11th and 12th 2020

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You know what I was going to do next week? Going to Washington DC and Teach a QGIS class.

You know what I’m doing now – Sitting in my house and teaching a class at Fed Geo Day on June 12th 2020

So what is Fed Geo Day:

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For decades open source software has been at the forefront of innovation in data collection, analysis, and visualization. Today, open source geospatial software has evolved into an “open ecosystem” of software, communities, and companies that enable field data collection and advanced visualization and lead the way in drone, lidar, IOT, and satellite imagery collection and analysis.

When open source software is combined with open standards for interoperability, government agencies have the most scalable, stable, secure and cost effective tools available to support activities including:

  • Empowering disadvantaged communities with limited funding
  • Enabling real-time data analysis at planetary scale
  • Optimizing release schedules for constituent facing tools

Join us for this one day conference in the heart of Washington DC. The morning plenaries will share how open source geospatial tools have become a critical part of operations within multiple federal agencies. The afternoon break out sessions will tackle technical and management solution use cases.

  • $20 dollars gets you into the conference
  • $20 dollars gets you into the QGIS Class. There are a lot of training options beyond the Introduction to QGIS class.

Attend! Support Open Source in the Federal Space!

QGIS and Editing: Widgets

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I’ve been getting more questions lately on QGIS from all over the place. A pandemic will apparently: cause you to experiment with software, do some weird things with existing software, or call me up and ask “How do you work from home this sucks”. So one question started out with “I need to edit some data for the team and I need to keep up with what I edited and no it’s not in a database”.

In my perfect world you edit against postgresql/postgis and I set up some triggers to at the very least record who and when and possibly X and Y (or Y and X).  If you’re stuck with a shapefile, spatialite database, or Geopackage what can you do? So you have these things called widgets in QGIS……

So we’re going to play with a geopackage because that gives me some talking points for the next blog post. The ruggedly handsome client (me) has shoved some data into a geopackage. Geopackage has no login so I’m going to add my data to QGIS and do the following things:

  • Add two fields called ‘edituser’ and ‘editdate’
  • Set up two widgets in your QGIS Session.

If you right click on a data layer and go to properties you can set up a widget for your fields (under Attribute Forms). A widget can be a drop down list (something like a domain on a subtype for you over in ESRI Land).

So for the edituser field I will pick a simple text edit widget with a default value of ‘rjhale’ (At the Bottom of the menu).

The editdate field gets slightly more complicated. For that one I reach into the myriad of QGIS functions and pull out the $now. So I apply it as a default (and check that I want it to update if I move the line):

 

So moving forward I can at least keep up with “who” edited and “when”.

That’s possible the simplest use case of a widget you can have. What if you wanted to update the length of a line automatically? The QGIS Function is $length and you could apply that as a default to a widget on a field and have it calculate the length.

The big take away on this is you can do some very simple things to help your editing life. Two widgets with default values and you can keep up with what you’ve done (or maybe a co-worker) in an attempt to combine the data back together at a later time. A giant shoutout to Spatial Thoughts as I start to dive into more widget magic over the next bit.

 

QGIS Profiles

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I should probably start out technical posts going “Your Mileage May Vary” but the more times I did this the less worried I got about writing this post.

Anyway – It’s time for upgrades if you’re doing anything in QGIS land. Especially if you’re running a Long Term Release. QGIS 3.10 has had enough patches you should start using it. A client called with a problem in QGIS and I said “WELL LETS UPGRADE!!!!”. She did. QGIS Started crashing. QGIS wouldn’t save. Nothing good was happening. Of course I feel extra great about it all because I said “UPGRADE THERE IS NOTHING THAT CAN GO WRONG”.

All is not lost though. It’s actually pretty easy trouble shooting the problem.

QGIS has profiles. What’s a Profile? I’m glad you asked and I’ll refer you to the awesome documentation. In short – anytime you start QGIS you’re reading your default profile and that holds everything from variables/models/connections as well as plugins. Do I use profiles? Yes for the QGIS class because I want everything to be just like I installed it BUT I don’t want to loose anything I’m working on (So I’ll have a Training Profile and a default profile). Yes – Gone are the days where I’d gleefully just reset my install by deleting my profile.

If you start QGIS you can go to Settings -> User Profiles -> Open Active Profile Folder and all the details appear. Plus you get to see where this directory lives on your computer.

profile location
One of the few times I’ll show you a screenshot from a windows machine.

So how did we fix it? You upgraded and nothing is going right OR just some random QGIS weirdness happening. Make a new profile. I’m going to make one called “blog” by going to Settings -> User Profiles -> New Profile.

Guess what – A new folder appears along side the default (if you happen to be watching the directory where all this is stored).

You’ll also notice you’ve got a brand new session of QGIS that will open up. That brand new session will have none of your settings. WHAT? Yeah – you’re running a brand new “fresh” session of QGIS so you have no settings. No Database connections. No Plugins. Enjoy the untouched landscape of QGIS.

What happened with the client? I had them make a new profile and load their existing QGZ file using that new profile and it worked. Why? No idea. Maybe a plugin wasn’t happy. Maybe “some weird computer thing” happened. What I think happened – and this is pure speculation on my end: They were running 3.4 LTR and had been negligent in installing the patches that are issued once a month. So their copy of 3.4 was pretty old plus they hadn’t upgraded plugins……and then suddenly we jump to 3.10. If I were sitting there I probably would have upgraded plugins and maybe installed the last release of 3.4 before trying the 3.10 release. I’m weird that way and that’s not complaining about QGIS’s installation process. Things happen.

How do I make it even easier. Close QGIS. Rename the default profile folder to default-old. I rename the blog profile to default. Copy the QGIS folder, bookmarks.xml, qgis.db, qgis-auth.db, and symbology-style.db over to the new default profile out of the old one. Usually I just re-download the plugins. If I have QGIS models I’ve made I will move the processing folder over.

Do I use this “one neat trick” a lot? Not really…BUT if you ever get to a point where QGIS is crashing or not starting right make a new profile and see if that straightens things out. At the end of the day I have three profiles:

  • work
  • blog
  • training

The one thing I enjoy with the profiles: If something is really being weird on the client’s end I can have them zip their profile up and dropbox/email it to me. I can use it and then pick at it a bit and come up with an answer. I can pull someone else’s QGIS session into mine and trouble shoot some problems they have. How often do I use that? Not often…BUT when you need it you really need it.

So – QGIS Profiles. Read the Docs! Make a test profile “just because”.

Stay safe out there.

 

 

 

 

 

May 2020 Training Rescheduled for June 2020

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Well – this is all weird.

The Upcoming class in May is pushed off to June 24th and 25th. Hey – Is this a good idea? NO IDEA. I figure in about a month I’ll know whether to cancel it or go ahead with it. Of course we will be following the Guidelines of the CDC, Chattanooga State, State of TN and whoever else we can follow.

With that said – I’m starting to reformat the class for “virtual”. The class is built for in an person trainer and with that looking rather grim these days. I’m working on a slightly different setup using zoom/skype/something to work through the material. I could continue talking about that – but I’m pretty much tired of discussing virtual type of things as I suspect a good portion of you are.

Anyway – back to work. If you do wish to show up in June for a class – it’s 2 days in Sunny Chattanooga. We may knock off class early the first day and go canoeing.

Length of workshop: Approximately 16 hours

Topics Covered:

  • Interface
  • Vector Data
  • Raster Data
  • Plugins
  • Processing Tools
  • Field Calculator
  • Exercises Throughout

Registration: https://www.campusce.net/cscc/course/EventDetail.aspx?C=106

Cost: $700

Anyway – Good People Stay Safe and Learn some QGIS.

QGIS 3.x: Setting up a Project

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I’ve been digging through the QGIS class this week as I wrestle with a way to move the class online. While doing that I started filing in the gaps of things that I wanted to add but didn’t because of time. Well – with the class moving online I can add more things.

Usually what we do when setting up a QGIS project is:

  • Open QGIS
  • Toss a bunch of data in it
  • Save it somewhere
  • Come back to it later

So for those of you just starting out or maybe for those of you who have been working with this for a while – a helpful hint.

Open QGIS. Slow down and go to  Project -> Properties -> General. We are only going to look at 3 things in this – so don’t worry. This won’t be anything complicated.

You should see this:

qgis project properties

We’re really going to worry about two things:

QGIS project properties

When setting up a new project I always do one thing to kick off the event. I build a directory structure to start storing scripts and maps and anything of use.  I set the Project Home (above) to be that directory. I also set a working project title like “My Map” or something.

qgis working project

I also go ahead and set the Measurements. I know this project will be in a local planimetric projection so I’ll set that to None/Planimetric and since my world revolves around Feet/Square feet I’ll go ahead and set that up.

The next thing I do is set up the Coordinate system – so click on the CRS Tab on the left and set it to whatever you need it to be – in my case EPSG:2274

project properties CRS

I click Apply or OK and the last thing I do is Save my Project (back to the Save Project portion under the Project menu of QGIS) . That last save leaves you with a complete Project Properties.

Completed project properties

So who cares right?

Well if you happen to use the browser panel you’ll notice something has changed:

project home in browser

 

Project Home now appears  – which means I have quick access to everything I need from shapefiles to geopackages to imagery to whatever. Right in the browser which really gives you a ‘Workspace” feel for your project.

How long does it take to set up? Not that long but the benefits of getting that one small part done outweigh the time you’ll spend setting it up. I’ve been bitten many times by having the wrong units set up or something else that could have been taken care of by spending 1 minute setting this up.

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