QGIS

I’ve started working on my Edinburgh Paths Network Map again. The last thing I did was update the extent of the line layer that represents the paths themselves. The next thing I’m going to do is split out the access spurs (the little entrance / exit bits) into their own layer.

Initially the paths line layer contained only 88 features. Then I went wild and extended it much further than I’ve explored in real life which came to 830 features. Then I reigned it back in a bit and currently it contains 239 features. This is a better starting point. It’s the amount of path network I would show to someone visiting Edinburgh who wants to go for a nice walk somewhere. Thus I’m calling it the primary path network. This leaves room for expanding it later with another layer perhaps, likely called secondary path network or something.

So it’s back to QGIS to split my primary paths network layer into two. A bunch of zooming in and out and panning and selecting later… now I have 153 features in the primary path network and a new access spurs layer with 86 features.

Tip: hold Ctrl while zooming in and out and QGIS will zoom in and out slower. Conveniently you can also use Ctrl + Click to select features, rather than using Shift + Click, so you don’t have to hop between the two keys.

The new access spurs layer is a bit rough. I appear to have missed a few tiny path segments here and there (usually stairs it seems). Fixing those later will be a good exercise in updating one of my line layers with fresh data extracts from QuickOSM. It’d also be useful to combine some segments together into a single feature I think. That way a specific access spur can be selected and treated as a whole. But then I’d lose the possibility of showing certain information. Like whether a chunk of stairs in the middle of an access spur has a handrail or not, for example. Hmmm. Not a decision for today though, just a thought.

Ok next up is updating the web map with the spur-less primary path network and adding the new access spurs layer. Added the new GeoJSON files. That was sufficient to trim all the spurs off the current map. Now to put the spurs back on the map, but this time in their own separate layer that I can style separately. Ok done. Now to style them differently and only show them once you’ve zoomed in closer. Done and done.

Jolly good. I have a whole raft of ideas for things I’d like to try with this map but I’m not sure what I want to do next. I’ll probably revisit the green circles currently marking “access points” first and clean them up a bit while I consider the next thing.

• my brother’s flat hunt is thoroughly complete now as i helped him move into his new place last week! he was indeed pleased with it, which pleased me, and the rest of the family too. crisis averted, phew!
• i finished the PyQGISChallenge! mostly! i’m about half way through putting together a toy plugin as the mini project for the last couple of days. i’ll post about that specifically once its done.
• and i sorted the last bit of OS upgrade aftermath, which was sorting out my geolab database again. this involved an excursion into the land of containers, which i haven’t visited for a while, to extract my postgres 13 database for loading into my new postgres 15 database. now everything is pretty much as it was a few weeks ago. jolly good!

• the flat hunt is complete! woohoo! next stop, moving day
• so very glad the flat viewings will cease. there were fun days, but also tiring days. i’m really happy with the flat my brother will be moving into, it will suit him down to the ground
• saw Death From Above 1979 in Glasgow last week and it was damn good – the 20 year anniversary of You’re a Woman, I’m a Machine so they just played the album start to finish, and then some new tunes i’m less familiar with afterwards
• had some dinner at Buck’s Bar before the gig and was defeated, in the sense i had to use a knife and fork to consume the burger, i felt shame, very tasty though
• started the PyQGISChallenge from Spatial Thoughts – the same idea as 30DaysOfQGIS in May, but this time going through the PyQGIS course materials

• created a new “notes” section on my website. i don’t know exactly how i intend to use it yet, i just know i’ve occasionally wanted to refer to one of my obsidian notes in a blog post. but i don’t want to create a separate blog post for the note to do that, and my “lab” section doesn’t feel like the right place either (its kinda more for technical stuff). i guess the gist of it is i’ll slowly turn some private notes into public notes.
• made some plans for a series of projects and blogged about it: data pipeline plans
• worked on my geolab database bootstrap scripts, per my data pipeline plans.
• played around with Model Builder in QGIS for the first time (via 30DaysOfQGIS). i like it.

• i haven’t wrote a weeknotes post for months, so i wrote the script i knew i’d inevitably write to tell me what week number i should use, as per my new naming convention described in weeknotes 60
• i’ve started following along with 30DaysOfQGIS from Spatial Thoughts as lately i don’t feel like i’ve spent enough time doing stuff in QGIS, so this should tend to that
• implemented “collections” logic on osgav.run – now the “blog” vs “weeknotes” split on my homepage is powered by a collections frontmatter key rather than the type one. the theory behind doing this is i can link sets of posts together and call them a collection or series (or just call them categories, the classic accompaniment to tags) and then have links to “other posts in this collection” at the side of a blog post. adds a form of discoverability to things without me having to explicitly link to related posts. not implemented that bit yet though. coming soon™

$ python build/what-weeknotes-is-it.py

use weeknotes-97 for Wednesday 15 May 2024      [1 days ago]

today is Thursday 16 May 2024

use weeknotes-98 for Wednesday 22 May 2024      [6 days away]

I did a thing the other day and the result wasn’t quite what I was aiming for. But it was reasonably close and looked nice anyway. I shared it on Mastodon and in the replies I was introduced to The Glitch Gallery. Now the thing I did is published in The Glitch Gallery. Wahey!

I was experimenting with Simplify in QGIS the other day and I wanted to get an idea of how many vertices were being removed from my geometries when I adjusted the Simplify settings.

I woke up thinking about a fragment of a map the other day, and it occurred to me that what I was picturing could probably be made using geometry generators in QGIS. I was picturing something like this:

So I thought I’d have a whack at making it.

Things I got up to in the last week:

• published blog post: systems, processes, and tools
• read an essay on systems design: https://apenwarr.ca/log/20201227 (via this tweet)
• phone link dump, all the way down to zero tabs open…
• got stuck into Observable Getting Started guides and the like and…
• started playing with my own dataset on powerplants
• did more of the Esri Cartography MOOC (running a bit behind, need to catch up!)
• discovered, fixed an issue with, and blogged about QGIS MapSwipe Tool Plugin
• published blog post: Spilhaus World Ocean Map
• started drafting up a new About page for my website (I’ve just had placeholder text there for a few years now…)
• started shopping for proper storage for my atlases and maps collection
• signed up for OpenStreetMap!

And some more words about a few of those…

I’ve been using ArcGIS for the first time in the last couple of weeks and I’ve come across the Swipe tool. My immediate thought was “oh that’s awesome” which was swiftly followed by “I wonder if QGIS has this as well?”

Last month I took part in my first 30DayMapChallenge – a daily mapmaking challenge that takes place in November each year.

For the graded assignment in the Introduction to Mapping, Spatial Data and GIS course I completed in June I made the following map:

Things I got up to in the last week:

• GEOG 868: Lesson 5: Working with Esri’s Desktop Geodatabases
• read some of my BCS cartography book
• accidentally started a website redesign project

Some rambles about each of those:

In Lesson 4 of GEOG 868 I completed a site selection using PostGIS.

The Making Maps unit for the Introduction to Mapping, Spatial Data and GIS course I completed in June featured a tourism case study. The exercise that week was to create a tourist map of Melbourne in Australia.

In Lesson 3 of GEOG 868 I played around with PostgreSQL and PostGIS for the first time. For the project at the end you are given a class_roster.txt file that contains a list of students and their postal codes. The task was to join that with data provided earlier in the lesson and then plot the students’ locations on a map in QGIS. Here’s how I went about doing that.

As noted in Hello (GIS) World I was recently working on the first assignment in the QGIS Training Manual. I planned to do 3 things for the assignment:

I am exploring the world of Geographic Information Systems (GIS).

I have been reading the Gentle Introduction to GIS from the QGIS documentation and also working through the QGIS Training Manual. In the last couple of weeks I completed the first assignment.