July 13, 2024

PDF page overlay with Go

Recently, I had a need to overlay 2 PDFs in Go.

Some background: I had a semi-complex PDF generated off-line with a Python program and I needed to overlay some simple drawing on top, on-demand using some parameters sent from a website. Since I wanted to deploy on Cloud Run (free for my low-traffic app), in order to avoid issues with cold start, I decided to develop the server in Go. The drawing part was simple: I used fpdf, which worked well.

However, I had a bit of trouble to find a way to overlay the generated PDF on top of the complex pre-generated PDF. Also, when I asked Github Copilot, it kept referring me to the Unidoc library, which is not free. At some point, I realized I could simply use pdfcpu and its watermark feature: It supports both images and PDF so it worked for me.

April 23, 2024

Migrating my blog from Wordpress.com to Hugo & Cloudflare

Migration

A few months ago, I decided to migrate my personal blog (former location) from Wordpress.com (free plan), where I had hosted it since 2008, to a static website (that you are reading now). The reason was that I noticed the ads really taking over the posts: There used to be a banner ad and ads at the end of the posts. But by accident, I browsed my website without UBlock and I saw there were so many ads in the body of the post. One option would have been to go with the paid Starter plan (currently $5, their cheapest paid offering). Instead, I decided to move to a static website.

July 25, 2019

Offline hiking maps with QGIS 3 and Geopaparazzi

In this post, I will show how to export background maps (as a set of MBTiles files) from QGIS 3 and import them in Geopaparazzi on Android to serve as backup offline hiking maps when far from civilization and mobile coverage.

It can be useful in France, where interesting maps to have while hiking are the IGN ones like Carte Topographique IGN (Scan 25) or their standard map (Scan Express Standard). They are accessible freely through the Geoportail mobile app. Unfortunately, the app doesn’t support offline mode.

March 17, 2018

Freehand Raster Georeferencer plugin updated for QGIS 3

A few weeks ago, I updated my Freehand Raster Georeferencer plugin for the newly released QGIS 3. I also included a few fixes for some issues as well as new features such as uniform scaling, a new “Georeference with 2 Points” tool (contributed by a user) or taking into account an existing world file. Those changes were backported to the plugin version for QGIS 2 so there should not be any difference between the QGIS 2 and 3 versions. See the updated doc for information.

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September 11, 2016

Innov-Agri 2016

Innov-Agri is a large outdoor trade fair for agricultural machinery and equipment. In 2016, it took place in a field near Orléans. A lot of constructors were there and offered live demonstrations of their products. The company I work for was an exhibitor so I went there on the first day of the fair. I walked around and took a few pictures.

July 22, 2016

"Freehand Raster Georefencer" plugin for QGIS

Some time ago, I released a plugin for QGIS called “Freehand Raster Georeferencer” that allows interactive raster georeferencing. It implements some tools (move, rotate, scale, stretch…) to manipulate a raster directly on the map, on top of the other layers. This is in contrast with the standard raster georeferencing tool of QGIS, which needs control points and then an export to be able to check the georeferencing.

November 19, 2014

Paris in 3D with QGIS and three.js

Some time ago, I saw this article about using the Qgis2threejs plugin to export a QGIS map as a 3D visualisation in the browser, thanks to three.js and WebGL. When I recently tried to follow the post to reproduce the results, I had some problem sourcing the data (related to Vienna, Austria) so instead I searched for data related to Paris to create a similar scene. Here is the result corresponding to the screenshot above and another one with aerial photos, both showing the Montmartre area of Paris.

February 1, 2014

Tokyo Ramen Map on the Android app store

I released a free app called Tokyo Ramen Map a few weeks ago on the Play Store. It is a simple map application showing all the ramen restaurants in central Tokyo, along with ratings. I built it for my needs so it is quite bare bones. The main point was to make it work offline since I don’t have a data connection outside my apartment.

December 10, 2013

iBeacon on Nexus 10 with Android 4.4

Android has added support for Bluetooth Low Energy (aka Bluetooth Smart) and thus iBeacon (a profile of BLE) in version 4.3. However, on my Google Nexus 10 (2012 edition, now running Android 4.4 aka KitKat), support is disabled in the official version provided by Google, even though the hardware supports it. Since I want to try out (and maybe develop) apps that use iBeacons, that makes me very sad… Thankfully, there is a way to enable it, by replacing the original Bluetooth-related libraries on the device with patched libraries that add support for Bluetooth Low Energy.

October 3, 2013

Apple iBeacon

Recently, I have been researching techniques for indoor positioning, where GPS does not work. Although it is not widely deployed yet, one technology that looks quite interesting is called “iBeacon”, an Apple-designed (and currently unofficially documented) profile of Bluetooth Low Energy.