Data

QGIS 3.x: Setting up a Project

rjhale · Apr 7, 2020 · 2 Comments

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.

QGIS 2.99 – Data Source Manager

rjhale · Sep 11, 2017 ·

Notice I didn’t say QGIS 3.0 – I’ve been playing with 2.99 and it’s not ready for prime time – so don’t start working with it then go “But Randy you wrote about it! So I downloaded it to use in production and sometimes it doesn’t work and everyday there are updates”. That’s because it’s 2.99 and Not 3.0.

Post FOSS4G I’ve had some itches to scratch. Part of that has been diving into some technical things I’ve been wanting to work with. I’ve done a slight dive into Docker. I’ve been reading up on R. I’ve been working with PDAL.

The other thing I’ve been doing is jumping back into QGIS. I’ve been distracted with a lot of other things with work like “paper work”. The good news is I won’t be going to jail for tax evasion or screwing up client’s work. The bad news is you are stuck with me a bit longer and I feel like typing.

One of the things I remember from the intro to QGIS class is “button pushing” – as in “How do I add data?”. ArcGIS Desktop has the one all-knowing button. QGIS has 12 buttons if I don’t count the Virtual Layer button. When I first started using qgis back in 1.8 it was a bit annoying. It grew on me. I will admit it’s a bit overwhelming for some people.

There is a button for vector, raster, postgis, spatialite, ArcGIS Mapserver Layers, etc. It seems about once or twice a year a discussion would start in the QGIS community of “We need one button to add data”. Emails would be exchanged and I assume some of the developers would talk amongst themselves.

Guess what?

Behold the “One Button”. That one button now opens the Data Source Manager. The data source manager combines everything (including the browser) into one menu. When I first started using it it was a tad annoying. I like it now. Plus it’s going to be a bit easier to explain “Open the Data Source Manager” vs “Click on the arrow next to WMS and Look for Add ArcGIS Mapserver Layer.” You can add data as you normally would or drag and drop it in using the browser.

QGIS 2.99 is still under heavy development – so I wouldn’t dive into it just yet. Just know that changes are coming – and they are pretty awesome.

“From the Trenches” talk at FOSS4G – Part 1

rjhale · Jun 28, 2017 ·

This will be a bit rambling. It’s been a while since I’ve put anything substantial up here because I’ve been busy. I broke it into parts because this started turning into a rant.

First off – I’m headed to FOSS4G in Boston to speak (and teach a workshop – but more on that in a bit). The talk in Boston is “FOSS4G from the Trenches” – I think. I really can’t remember what I said the title would be. I do know what I’m going to talk about.

The Crux -> Spatial is Special mostly.

I’ve said it and probably everyone else has said it -> Spatial isn’t Special. A few years ago it was the fun thing to scream. To a degree it’s true. 99% of my clients are running FOSS4G software these days. In some cases it was an economic move and in some it was a “We need a map” and they dove into PostGIS and QGIS. They didn’t spend a ton of time talking to sales and going to training. Then they call me. Why call me? Well it’s reported I know what I’m doing in this area – ALTHOUGH – I think this year has shown me I have a lot more to learn.

Three things really stuck out the first part of this year:

My skills as a “GIS Person” are relevant in one regard and irrelevant in another. Yes Spatial isn’t special as anyone can build a web app to run a buffer and return data. Until the data comes back wrong – then I’m special again.
No one is updating their software like they need to. It doesn’t take a rocket scientist to update their software BUT…..
I like data exploration and data science – BUT – building data from scratch isn’t irrelevant.

Part 1 – Skills.

Spatial is special and your data are important.

I’m dealing with three groups of people right now. I’m not even going to mention what software they are using. No – I will. ArcGIS, PostGIS, and QGIS with the data residing in Spatial Tables, File Based Geodatabases, and Shapefiles. Two are Utilities and one is a conservation group.

In every case: no metadata, no data lineage, and no thought to data completeness. I went on a rant a few months ago that Python wasn’t GIS – guess what – I’ll probably be scripting some of the data fixes….Assuming I don’t pull it all into PostGIS to fix it and then shove it all back into whatever data format people are using. In all of that I’m supposedly mentoring a couple of people and I refuse to talk about desktop software – I keep hammering on “get the attribution/data lineage right” then we will do analysis.

Another client went on a data collection binge. They bought a lot of hardware and are looking at collecting high precision data points in Fulcrum. Which led to a discussion on accuracy of phones and software and things in general with Bryan at Fulcrum. I’ve collected data with my phone. I’ve never much thought about the accuracy as I’ve always worried about the data I’m collecting. I always fall back to “well probably 40 feet (or 10ish meters)” and went back to my angry rambling about not owning an Ianything.

Anyway – I get the whole “spatial isn’t special” phrase – it’s not special because he software is everywhere these days. It’s not special because GIS is slowly fading into a tool for your chosen profession. Except here I am – my profession is geospatial and sometimes you need the grouchy guy to come in and scream at people and fix things that get broken and offer advice. Datum huh? Tables who? Projection says what?

Which brings me to my next rant – update your software. It’s not rocket science but……….

PostGIS and Me.

rjhale · Jan 27, 2017 ·

It’s about time to start the PostGIS talking….

Way back when I had a project and the company to which I was subbing tossed me into FOSS4G way over my comfort level. I had used open source operating systems off and on – most notably Linux (Ubuntu/Fedora/Debian) and OpenBSD. The project was PostGIS heavy and to be honest I was lost. You had geometry columns and other columns and these stupid foreign keys. ST Commands. Don’t get me started on those. “What do you mean I just can’t go ‘buffer this table’?”

Anyway – so started a slow-moving exploration of PostGIS. I realized this last weekend I still have a lot to learn and I have more to unlearn.

My first dive into PostGIS was a database for a forestry client. It took a week to combine and shove 100 shapefiles into PostGIS. Over the weeks I started normalizing the database. It’s been running pretty flawlessly for almost 2 years. The only thing I haven’t done is to set up some scripts to ‘age’ the tree stands. I never received all the approximate planted dates and I know how I want to do it but no incentive to make it happen now.

As of right now I’ve got 4 projects running in PostGIS. It’s a bit scary – I’m not that great at it. I am learning. I keep threatening to do a class on PostGIS to go with the QGIS one and I haven’t gotten quite there yet.

Anyway – expect more rambling up here on PostGIS. Some will be insightful. Some will be boring. Some will just be “here is what I did to fix this problem”.

Like today.

One of my clients wanted to go open source on their GIS. So they did. They downloaded all the parts and using QGIS they started importing data into PostGIS. If they messed something up they would pull the data out into a shapefile. Edit it. Delete the PostGIS table. Push it back into PostGIS. Before they called me wanting help they were inching along. Not a GIS person in the house – just a group of people wanting answers. That’s how easy this has gotten. Let that sink in for a minute. It’s a Geographic Information System and no one was “trained to do it”. It’s all open source also. Just read instructions, download, install, and start working.

Today I started normalizing the database. I moved everything locally and just started developing scripts to “fix” things. Which is another side to this I need to get better with – scripting. Why did we not normalize it before? They were busy building it out and I walked in at the half way mark. It is eye-opening how much time I spend making it right vs starting out that way. Of course I would argue that they’ve been working and answering questions with some degree of accuracy so it’s right (mostly).

I also started a database for a non-profit of their water testing points. In PostGIS. This may be the first time I’m doing this right from the start – which actually makes this 5 databases I have running in PostGIS.

Anyway – back to the problem. One of their point tables had kept the primary key but lost its sequencing. So when they added a point they had to manually go “42” for the primary key vs the database just pushing it forward one digit. It’s not the end of the world – just a terrible way to live in 2017. Ninety Five points total with the largest number being 100. Somehow they skipped 5 numbers.

So you know what – I rebuilt the sequence:

create sequence <sequence> increment 1;

alter table alter column id set default nextval(‘sequence’::regclass);

alter sequence <sequence> owned by <schema.table.id>;

select pg_get_serial_sequence(‘schema.table’, ‘id’);

select setval(pg_get_serial_sequence(‘schema.table’, ‘id’), max(id)) from <schema.table>;

So the next added point gets a primary key value of 101.

…and I know that’s a lot of stuff for one problem. Also – it has nothing to do with GIS – just databases. So I turned into a DB Admin for a moment. Sorry to the DB Admin I cussed so heavily back in 2007. I knew not what I was doing.

To end it – some of you reading this are going “OMG – We know about PostGIS you are so far behind”. Some of us grew up with flat files and other insanity and it’s only been the last bit for me that I’ve seen the light (so to speak) on data. Treat your data like a database.

With all of this PostGIS knowledge so now what am I doing? Building triggers (what’s a trigger?) and doing a lot of searching and reading. I’m Doing some analysis of the data. Fixing it. I’m importing Fulcrum data at times.

What am I getting out of all of this? Clients who get Answers. A decent knowledge base on databases. Some personal satisfaction which (truth be told) can get a bit thin when you’re consulting. At least with me.

Updating Roads in Chattanooga TN in OSM

rjhale · Jan 8, 2017 ·

I’ve been attempting to get better with PostGIS. I’ve also been trying to take baby steps back into the world of OpenStreetMap. I’ve also been trying to take baby steps back into my City’s Open Data Initiative.

Why? I’ve been away for long enough – plus – never quit learning.

I’ve only so many hours in a day. To be honest with my attempts at getting back outdoors and doing things that interest me, I’ve more or less stopped a lot of side projects. With the weather currently being disagreeable to most things outdoors I’ve decided to start diving back into a few things I’ve left hanging.

The OpenStreetMap group here in town is a bit hit or miss. We have a high school that maps. We have a few people diving in here and there. There’s no coordination to the madness and I tried, as did a few of us, to coordinate some of it. I finally gave up. So I do a *few* things in OpenStreetMap here locally but not much.

I made a decision to:

Map as many Churches as I can (more on that later).
Fix the Roads

Fixing roads is a bit of a chore. I hate touching interstates because I don’t understand the relations involved. There’s probably some “OSM Roads” email list but I just don’t want to get that committed. I’m happier working by myself for a bit or in smaller groups. I’ve also never took a look at the road names in OSM – I’ve worried with alignment but never “names”. About the time I was moving back into Chattanooga mom called, “They changed two road names in the neighborhood!”. I actually think road names had been changing for a while in the county as the County GIS department did their best to clean up confusing road names for 911 purposes. I *think* this data is then fed to the city or maybe the city is changing road names at the same time. Whatever the case – names are changing and it’s already fixed in Google Maps.

Chattanooga has an open data portal. I’ve been randomly mucking around looking at data and found the Chattanooga city addresses. I also found that they’ve already been donated to the openaddresses project. I downloaded them and loaded them into PostGIS. There are 102761 points. Each has a street address. I grabbed the roads from OSM and the city boundary from the open data portal. Through series of maneuvers in SQL that would horrify the more well educated – I actually compared the two and built some foreign keys and other things to make joins easier. Through that my favorite color scheme in the world – Red Green. Green is right as far as I can tell and Red isn’t.

What I did find:

my join was a bit sloppier than I wanted but overall I can pick out the problems between the Chattanooga’s address data and the OSM data.
I spent more time than I should have reading the FGDC Address standard – BUT – it helped (plus SQL examples).
There aren’t a lot of errors but enough. In some cases there was a completely new name applied by the city to a street. In many cases the road in misspelled in OSM (which is probably a holdover from the days of TIGER Data). Some are from the high school. They are great at editing but not so much at cleaning up. I need to work on that.
The cities address data extends into the county by about 1000 feet. Which means when I clipped my roads I lost some data I need and will need to fill back in. Thanks to the power of scripts and me being anal retentive – not that big of a deal and I’ll deal with it as it becomes an issue.

Of course the big question is “Is the cities address data correct?”. As a GIS person I say Yes. As a guy that has worked in GIS for 25 years now I’ll say “probably because I’ve talked to no one over addressing”. So I’ve making a list and print it out and over the coarse of the next few months I’m going to inspect many of the things I’m seeing as wrong. There are three on the way to my parent’s house. I’ll probably even hassle the city/county a bit for information. I’d like to get them more involved if at all possible.

Why fix it? Why not. OSM is enough of a force that it should get fixed – BUT – as GIS people our attention is diverted by what the clients use. You never hear someone say “Well I was using OSM to find my way to the mall…..” it’s usually “Google It” or “what does Google/Waze/Something else say”. It’s not that hard to fix problems once you have a list.

Anyway – more on this as the months progress. This will most likely occur “as time permits”.

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