I don’t seem to have time or energy for long posts these days, but here’s another quick post which might save you some time and frustration. Recently, I’ve been trying to import OpenStreetMap data into a PostGIS database to use with pgRouting. I wanted to import data for the whole of England – which has […]
A quick post today to talk about a couple of PostGIS functions I learnt recently. I had a CSV file that contained well-known binary (WKB) representations of geometries, stored as hexadecimal strings. I imported the CSV into a PostGIS database, and wanted to convert these to be proper PostGIS geometries. I initially went for the […]
I’ve been informed that this method is no longer working, and I haven’t had time to try and update it to work again. I’m leaving this here for historical value, and in case anyone can adapt the method to make it work. Microsoft Planetary Computer is a wonderful archive of geospatial datasets (primarily raster images […]
For a while I’d wished there was an easy way to get notified when my favourite open-source packages release a new version. I’d often see something on social media, but that tended to only be for the larger packages – and I wanted to keep up with the smaller ones too. When I actually bothered […]
I was looking through my past blog posts recently, and thought a few of them were worth ‘reblogging’ so that more people could see them (now that my blog posts are getting more readers). So, here are a few posts on matplotlib tips. Matplotlib titles have configurable locations – and you can have more than […]
I had a need to do some segmentation of some satellite imagery the other day, for a client. Years ago I was quite experienced at doing segmentation and classification using eCognition but that was using the university’s license, and I don’t have a license myself (and they’re very expensive). So, I wanted a free solution. […]
Summary: You can use QGIS expressions to set the default path for an Attribute Form to be something like @project_folder || '/' || 'MapGraphs', which gives you a default path that is relative to the project folder but also has other custom subfolders in it. I spent a while redrafting the title of this post […]
I came up with an interesting plan for an artistic map recently (more on that when I’ve finished working on it), and to create it I needed to be able to calculate a large number of driving routes around Southampton, my home city. Specifically, I needed to be able to get lines showing the driving […]
This is a bit different to what I usually post on this blog (which is usually technical content about GIS, remote sensing, Python and data analysis – see a few example posts), and this is part of April Cools – a group of bloggers writing posts that are unusual for them, but still good content. […]
Here’s a bit of SQL I wrote recently that had an error in it which I struggled to find. The error I got was ERROR: invalid reference to FROM-clause entry for table "roads" and I did some Googling but nothing really seemed to make sense as a cause of this error. My SQL looked like […]