North River Geographic Systems Inc

Spatial Problem Solving

QGIS

20 minutes at the East TN TNGIC Meeting

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I went through a year or so of not talking at conferences. For local ones I’d show up and do something. I taught a workshop at FOSS4GNA 2018. I did a workshop at FOSS4G 2017 in Boston (and it sorta sucked).  I need to get out of that mode and talk more – but I’m happier being quiet these days and working with clients.

Anyway – at FOSS4GNA 2018 I discovered something – the OSGEO Suite had disappeared from Boundless’s Website and was replaced with a github repository. It wasn’t long after Don Meltz put up an excellent explanation of the OSGEO Suite. The OSGEO Suite being gone isn’t a problem. It does increase the amount of talking I have to do spend explaining it’s not a problem. I could even compile the suite – but my clients can’t. They are smart people – but the time to compile the boundless suite won’t be happening.

One of the things I keep running into is the idea of an Open Source Server. The OSGEO Suite was well known and I get people asking “Hey – can you set us up a geo server”. They mean the opengeo suite. I then launch into an explanation of what makes up a “geo server” and they go a bit blank and answer me “Yeah – one of those”.

So for the next bit I’m gonna be doing something like this:

I want to explain how this works to people. We’ve gotten a bit deaf by hearing “ArcServer” at every conference in TN as this one monolithic thing you have to install to make a web map…which really don’t need since AGOL appeared but…you want SDE and it’s not called that and you have two people editing but you need SQl Server but you don’t….

Anyway,  QGIS/PostgreSQL/PostGIS I’ve installed multiple times and as of late I’m experimenting with geoserver and what it can/can’t do. I have no grand delusions of creating ‘Randy’s Open Geo Spatial Super Duper Server’.  I want to get to the point where maybe mapserver is an option in this. So much to learn…so little time.

I suck at github – but I’ve been more active as I try to develop a skill set and get over the angst of pushing and pulling things. I’ve built a vagrant box to install PostGIS/PostgreSQL/Geoserver so I can have something to point at plus it gives me a starting point for an upcoming class I’m in the middle of building. The vagrant box isn’t pretty – I expect to change it over the next bit as it’s mostly pieced together from a lot of other people’s work (Coleman McCormick, Dave Smith, etc). It works though and I have everything but pgadmin 4 running in one spot. Which – I don’t think this is anywhere near “install this for a server” because this is mostly just for talking, training, and testing.

So why vagrant? Why not docker? I can gloss over vagrant faster at theses talks than I can docker.  I have 16 minutes to draw diagrams and about 4 minutes to publish one piece of data: QGIS -> PostGIS -> Geoserver -> Leaflet.

Anyway – if you’re up for the possibility of a train wreck of a presentation come by the East Tennessee Meeting in Kingsport next week as I try to explain how this works and hopefully you get excited enough to install some or all of these components and do something cool with your data.

OSGEOLive 12.0

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So for those of you going “HEY I WANT TO USE SOME OF THIS OPEN SOURCE SOFTWARE?”. Maybe you can’t install it locally…or maybe you have a spare machine laying around – there’s a way for you to do it.

Download the OSGEOLive image and run it as a virtual machine or boot your computer into the Distribution. It’s a Linux operating system with about 50 plus free and open source geospatial applications. 

They put a ton of effort into releasing this as a showcase of the software in the OSGEO realm. So give it a run and test out software you have questions about.

Adding Triggers to Geopackage

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In between work I get a chance to play around with software. I’ve been digging around postgis more and more these days trying to get a better understanding of what it will do or won’t do. It’s a never ending learning experience for me. Sometimes it pays off – the never ending tutorial left me suggesting we dump a database to a geopackage.

I’m great at using geopackage in sentences like “USE GEOPACKAGE” and “Hey – what do you think about geopackage?”. Since I’m actually officially using it I decided to do some digging. It’s a SQLite container. Since it’s a SQLite container I should be able to do some things with it – like…..

spatialite gui

I can use the spatialite gui and throw SQL against it and change the tables.

While talking to another person the question started with ‘Well – why can’t we just do the data collection in geopackage?’.  Which we did some back and forth and in some cases this would be acceptable vs doing a full postgis install.

So my first question is: Can I make a trigger in a geopackage? The answer is yes. For those of you who don’t know what a trigger does – it responds to some action in a database. In postgresql, I put multiple triggers in a database for a client. Some triggers calculate lengths and some areas and some make a note of who edited a feature.

After some digging I found the syntax and wrote a trigger for SQLite/Geopackage in the form of:

CREATE TRIGGER update_esn AFTER INSERT
ON addresses
BEGIN
update addresspoints set “esn” = (select esn from polygon where st_within(new.geom, geom));
END;

I used the spatialte gui to add the trigger. So if I pass this off to a client they can edit an address and have it automatically pull in the emergency service number. Magic? Eh – close enough for me.

QGIS Screenshot

While it’s not going to work for a multi-user situation (or will it – I’ve not investigated) – it works. So now I’m adding widgets to QGIS to aid in data collection.

A tale of two FOSS4G meetings

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In the Spring of 2017 I had a small FOSS4G meeting in Knoxville TN and the general feeling after it finished was “When are we doing this again?”. So the conversation started and surprise – we had two meetings.

The first meeting happened in Knoxville on August 13th 2018. We had 9 presentations. The big headache I had with this meeting is it all comes down to sponsorship. I wanted it cheap – but I didn’t want to do in the hole again to do this. So we had sponsors. We also had a $10 dollar charge that could be offset with a scholarship if needed.

We had right around 50 people and covered everything from postgis tricks to measuring vegetation in the Great Smokey Mountains with LIDAR.

The second meeting was in Huntsville Alabama on August 14th 2018. The GIS Association of Alabama stepped forwarded and covered all the expenses. There was no charge for this one.

Fifty people came from the North End of the State to hear about QGIS, working with FOSS4G tools, and Jupyter Notebooks.

So what is the point? Actually is there a point? I sat around most of the day playing with how I wanted to summarize these two meetings. Meetings like this are hard. You have catering, a worry no one will show up, and a bigger worry no one will come and speak. We gave close to 100 people a chance to see something different. Which was double of what we did last year.

When I first started going to GIS meetings back in 1995 it was exciting. People would get up and speak and we’d all compare notes and figure out that we were all wrestling with the same problems. We were writing AMLS and buying workstations and digitizing old maps. Everyone had some sort of ESRI based user group. Maybe they were Intergraph. Maybe they had bought other software.

Flash forward to now and I’m consulting and not working for the Feds. User group meetings have morphed into these multi day extravaganzas that meet in your area…possibly not. You have to budget time and hotel reservations and it’s just a pain. So you end up not talking to your fellow geo people….or as we saw over the last two days people with specialties where geo is another trick in the bag.  Of course there is twitter and slack and facebook and linkedin and 100 different ways to talk to one another. What if you don’t?

So lets have a meeting centered around FOSS4G……or meetings. They don’t have to cost much. Maybe they cost $10 a person. Maybe they are free.  For Knoxville I poured about 2 to 3 hours a week over the course of 3 months…so about 40 hours. It wasn’t that hard – get a few people together and it’s less difficult. Find a low cost/free location. Huntsville had theirs in a courtroom. Knoxville had theirs at the University.

So in 2018 – I would like to get people together to talk about FOSS4G. Maybe you have a friend with a commercial solution in place for his organization. Maybe they have nothing. I think ESRI owes a large part of their success from the early days of getting people together to talk. We can do the same for QGIS/PostGIS/Geoserver/GDAL/etc. It’s a big world out there – you can mix and match about everything. I may not be able to make a North America Meeting (FOSS4GNA). Maybe these smaller meetings can scratch an itch for people and I can do that instead.

There’s no one to tell me I can’t. So what am I going next year? Workshops and a meeting in Knoxville. It sounds like the same thing will happen in Huntsville.

Rolling out PostGIS/QGIS Part II: Load your data

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I did it – I’m at Part II. I actually did it. Wooooooo. For some of you – this isn’t news – but – for some it will be.

For the Record – Part 1.

So you’re sitting with a client and you’ve documented and asked “WHY” so much they really want you to leave – it’s time to start loading their file based geodatabase into an actual database. Here’s where it gets weird for about 5 minutes. In those 5 minutes where you’re getting ready to load data you really need to look at your client (hopefully sitting with you) and go “OK – you’re no longer calling yourself a technician – you’re a database person now”.  They flip. You attempt to calm them – but yes – database person. Which isn’t particularly appetizing but this pile of data you’ve been hoarding in flat files for a good bit is a geographic database.

Most of the database admins I know are actually weirder than I am – which says a lot. One of my most spectacular “butt chewings” as a federal employee was the one time I did something to an oracle database and broke it. The admin had a fit. So much so when the yelling stopped several people told me “it’s not you – he’s on medication for this type of thing – you know – oracle DBAs and all – it happens so don’t take it personally”.

If you search the internet using Google for “Load Data into PostGIS” here is what happens.

google results not using qgis database manager

To spare you some reading – the first return mentions shp2pgsql. Actually most of the returns on the search will mention this. So much so you might think “I’m going to dump this file based geodatabase out to a shapefile and load it”. Don’t. For the sake of not over explaining this part – open QGIS and  use your browser to navigate to your file based geodatabase and QGIS will read it. Same with shapefiles. Same with about anything. If you’re leaving the land of file based geodatabases, as my client was, here we sit with a way out. Add that data to your map display in QGIS.

qgis screen

If you open the Database Manager in QGIS you can do quite a bit with the data. If you have PostgreSQL/PostGIS running (as we do) you can connect to it and import data. You don’t have to make a jump to shapefile then load your data. You can do it here. Reproject, define primary keys, and apply spatial indexes all from a user interface. With one click your data gets pushed into postgresql/postgis. For a lot of my clients and potential clients this is unknown magic. Your data will change just a hair. Lower case your columns for the love of all that’s good in the world. Apply spatial indexes. Document if something significant changes.

So go back to my second paragraph where I went “you are now a database person”. You’re taking all these flat files or flat tile structured things and making them interact with each other via  Spatial SQL. Which – not that big of a deal if you’ve got a full enterprise commercial roll out of Something Something Server Enterprise. It is a huge deal if you’ve never been able to do that. You get a large set of tools at your disposal you didn’t have before – plus the tools with QGIS you’ve got something very flexible in the making. Go ahead and order those books you’ve been eyeing. Join a listserve or three and ask questions. I still suck at SQL – but less than I did a few years ago.

There are still a pile of things to worry over like ESRI’s subtypes and domains and projections. Maybe you’re projections aren’t right. Maybe there is raster loaded in this File Based Geodatabase.   What about permissions? Editing? You’ve just upgraded your Geographic Information System from a bunch of files to a database. With great power comes great responsibility – so you need to jump back into learning mode.

………and where does that lead me – to Part III and “Hey why did my attributes turn into numbers you said this was just pushing a button?”

 

 

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