How to successfully run nextcloud in a subdirectory

Michael Demetriou


I run a local nextcloud instance for "cloud" storage. I have installed it in but nextcloud complains that

Your web server is not properly set up to resolve “/ocm-provider/” Your web server is not properly set up to resolve “/ocs-provider/” Your web server is not properly set up to resolve “/.well-known/caldav”. Your web server is not properly set up to resolve “/.well-known/carddav”.

Adding this .htaccess file to the root of my webserver (or it's contents in the apache configuration) solves all these issues.


Pixelfed installation on ubuntu 16.04

Michael Demetriou


This is a guide on how to install pixelfed on ubuntu 16.04 since that is a distribution most probably to find on cheap VPS's.


In most servers this stuff is pre-installed, but when you just install ubuntu server with no extra options they are missing. There's no harm trying, worst that can happen is to get an "already installed" message.

In some cases (minimal default installation) you will need to add the add-apt-repository command. I also had to install the https transport for apt (that is a program that allows apt to download over https instead of http) because some newer...

Smooth timelapses with ffmpeg

Michael Demetriou


Smoothing timelapses with ffmpeg

During shooting of the Rosalind videoseries we had the idea to include a timelapse of our lunch in each episode. It's fun and it provides a kind of intermission in the middle of the video so our viewers can take a breath amid all the technical information.

These get to be quite long and it's nice to speed them up with this command:

ffmpeg -i input.mkv -r 16 -filter:v "setpts=0.25*PTS" output.mkv

When you do however all motion blur goes away and the video looks kinda choppy. Increasing the framerate is one option but it doesn't work when you just want...

Tech team new year's resolutions

Michael Demetriou


Happy New Year

It's 2019 but off-world colonies and nexus replicants are still ways away, but here we are planning once again for the future. This is a writeup of our tech team's general goals and plans for the year. The main theme is exploring new technologies, publishing our efforts and advancing engineering software.


Being spread too thin is always a recipe for not accomplishing anything so I've decided to consolidate things a bit, though arguably these are still (over-?)ambitious goals. Our projects for the tech team here at d-e are three-fold:


Rosalind is...

Packaging and developing python projects with nested git-submodules

Konstantinos Demartinos



The present article aims at discussing basic operations that might be relevant to packaging and developing python projects with nested git-submodules. The motivation stems from an actual case that can be abstracted as follows:

We want to work with a git repository that has nested git submodules of an arbitrary depth.

This can be further analysed in the following use-cases:

It should be easy to update the superproject after any revision in the nested submodules. Packaging of the superproject should depend only in the upstream repositories of the nested...

Portable multiple font weights in LibreOffice and AutoCAD.

Michael Demetriou


What's wrong with the situation as it is?

LibreOffice for mac recognizes (as it should) font weights other than bold as styles of the same font and not as separate fonts. I.e. fonts can have than the 4 standard styles. (Regular, Italic, Bold, Bold Italic).

On windows the system does not support anything other than the 4 standard styles so other weights appear as different fonts (E.g. Source Sans Pro Light).

Thus this causes incompatibility between platforms. A style set to Source Sans Pro Light in Windows does not show up correctly on a Mac.

While GNU/Linux does support multiple...

Create beautiful visualisations of your structural models with blender and sketchfab — part 2: interactive experience.

Michael Demetriou


If you'd like to present your 3D model to your clients, or even the public, the best way is to serve it through the web. The easiest way to publish a 3D model on the web is either through sketchfab or host it yourself using blend4web. Each has its own set of advantages/disadvantages.

Sketchfab Built in blender One click publish Tweak lighting and materials after publication Embed in social networks Does not require hosting Blend4web Quicker to iterate (you don't have to wait for upload/preprocess) Works offline (if you are going to a meeting, that's important) Open Source You can...

Create beautiful visualisations of your structural models with blender and sketchfab — part 1: renders.

Michael Demetriou


Exporting your model

First off, you have to export the mesh of your model in 3D from the structural software of your choice. We use SCIA engineer here at the office, so these are the instructions for that.

Open your model Choose Structural Model from View Set view parameters. This is required in order for SCIA to export solids and not linear elements. Choose Export Graphic Format In the window that appears choose wrl as file type. Converting the model in a format that Blender understands.

While Blender does have a *.wrl importer, it unfortunately hangs when presented with a...

Cast from any computer to a raspberry pi using vnc

Michael Demetriou


We have all kinds of computers in the office. Some of them support airplay, some Miracast and some none of the above. I wanted a universal solution that works for all these computers, wired or wireless regardless of OS or hardware. Long-standing protocols in the rescue, once again:

A raspberry pi connected to the office tv along with vncviewer and any vnc server on the client will do.

Here are some scripts that make this whole thing a one-click process. Remember there's no sanitization or encryption going on. It's for use behind the company firewall.

Sorry, your browser doesn't support...

Export high quality images from draftsight or autocad to (libre) office

Michael Demetriou


We have been having issues with exporting things from drawings to reports. Either the quality is not good enough, or it involves too many steps.

One solution that works well and that doesn't involve too much effort is to go through pdf. Pdf export is usually very good in most CAD programs and from there, you can easily convert to image in any resolution you might want.

Why not export directly to png, you ask. Because usually resolution/crop is dependent on the monitor resolution and window size, which produces awful results except if you have a super high resolution display.

Hence, on...

Start a 500px slideshow from your bookmarks bar

Michael Demetriou


Unfortunately there is no simple app that just slideshows nice images from 500px.

Drag this bookmarklet 500px slideshow to your bookmarks toolbar to start one.

You'll have to be in a page that looks like this, for it to work, so go to your favorite gallery (e.g. popular) click on the first image, then again on it's center (where the cursor becomes a magnifying glass)

and then click the bookmarklet. If you'd like to change the duration of each slide, just edit the bookmarklet and change minutes=5 to your desired value

Finally press F11 to view the slideshow in fullscreen.


If you...

Write your reports in Markdown

Michael Demetriou


I hate word processors. I hate them because if I didn't know better I would bet that they are non-deterministic. And after seeing how people use them, I hate them even more.

I wish I could persuade everyone to use plain text but as that is impossible, I just try to use plain text myself where possible. However being involved with design stuff, I also love my styling.

Markdown with css is the way to go, but what if you need to adhere to the company report template, or you need to share as "document" with some others before finally outputting to pdf?

Pandoc to the rescue. I just...

Quickly share selected text with qr code on Linux

Michael Demetriou


Install xclip and python-qrcode, go to your DE's shortcuts applet and add this to any hotkey you fancy

xclip -o | qr | display

I chose Super + C and when I hit it, any text I have selected pops up like this: